Call it the millennial decorating difference. More-mature Americans, who didn’t learn their ABCs on an LCD screen, cringe at the prospect of an unwanted sofa hulking in their homes, and the anxiety of coordinating its removal. “Older people still like to see and feel, especially with a significant investment,” said Jennifer Mapes-Christ, a consumer-goods analyst with Freedonia Group. Millennials, on the other hand, “are in that digital universe, integrated into the idea of buying and returning and it’s not a big deal.”

For shoppers of a certain age, that need for tactile testing is a huge deal. That and an unfamiliarity with “millennial brands” that market via social media are keeping them from taking advantage of the efficient, direct-to-consumer, mostly digital companies disrupting the furniture, mattress and housewares industries. People over 45 buy only about a third of Brooklinen’s luxury bedding, for example. Still, that 4-year-old company, which opened its first pop-up shop in New York only last month, says it recently reached cumulative sales of $100 million with a strategy common to these upstarts: competitive prices, a carefully tweaked customer experience and generous return options that minimize risk.

Sites like Brooklinen are obsessed with keeping buyers satisfied for mostly one reason: the threat of social media backlash. A disgruntled purchaser can tweet dissatisfaction that goes viral. “That’s death!” said Edgar Blazona, founder of BenchMade Modern, which sells custom sofas through its website. “We do everything we can to not get that scenario. Sometimes it stings, it’s expensive, but we do it to inspire confidence.”

Another obsession? Uncluttered web interfaces. Companies that interact with customers mainly via the internet seek out an aesthetic that’s more editorial than commercial. Products are crisply silhouetted against white backgrounds, airily presented in rows of two or three. Language is spare and charismatic, as in 5-year-old furniture brand Article’s note on their newsletter email: “We’re not clingy: you can unsubscribe at any time.”

Some non-millennials have already discovered the millennial sites. This spring, Larry Olmsted, 52, bought a nine-piece patio dining set of coated aluminum from Yardbird, a Minnesota-based brand selling outdoor furniture. “The site itself is better and more well-thought-out than mainstream sites I looked at,” said the Hartland, Vt., author. He found the year-old company’s narrow selection—another telling sign of millennial retailing—limited, but in a good way. “Trying to sort the options at Wayfair and Overstock was oppressive.”

Sites like Yardbird typically launch with a non-mind-numbing offering and expand collections as they grow. Newcomer Dims. currently offers just four tables by five up-and-coming designers and will add seating in early 2019. Joybird, acquired by La-Z-Boy this summer, began in 2014 with 10 collections and, after reporting $55 million in annual sales in 2017, now offers 35.

The prevailing aesthetic tends toward the contemporary and clean-lined, hardly everyone’s taste. “The once-niche modernist market overall has grown significantly in the past decade,” said BenchMade Modern’s Mr. Blazona, but he’s not opposed to selling a rolled-arm love seat if demand merits it. “As our customer demographic evolves, ages or broadens, we would certainly consider adding more traditional styles.”

Simple decision trees help you make your choice, as do generous policies about mailing customers material samples: Sixpenny will send gratis one wood sample ($5 each for more) and swatches of all of their 37 fabrics.

Transparency rates highly for a typical millennial site. Along with the specifications for its assembly-required tables, sofa and platform bed, Floyd includes line drawings depicting exactly what pieces will arrive and in how many boxes. At Burrow, a model photographed recumbent on one of its couches is helpfully identified as being 6 feet, 1 inch tall, preventing surprises of scale.

Love of planet is a factor, too. When Yardbird co-founder Jay Dillon researched factories in Asia to source his furniture, he was so appalled by plastic litter he saw along the waterways that he vowed to incorporate the stuff into his product. His site reports that Yardbird used 30,000 pounds of intercepted ocean plastic in its outdoor furniture and packaging in 2017 alone. Joybird partners with conservation groups and says it plants more trees, reportedly 389,896 to date, than are used to manufacture the furniture sold.

The responsive customer service typical of these brands begins on their respective sites. “I love the chat boxes,” said Tara Blackman, 30, an ad-technology sales executive who’s bought several large pieces, including a $2,000 coffee table, sight unseen. “They’re the little thing that pops up and asks, ‘Can I help you?’ ” Many companies email you a transcription of your chat so you won’t get caught in a “but your customer service said…” debate.

Simple graphics compare the efficient direct-to-consumer model to the conventional retail supply chain. Mr. Blazona, an alum of Pottery Barn and Restoration Hardware , describes the typical retail-store process: “A wholesaler buys a sofa from a factory for $1,000, marks it up to $2,000 and sells it to a retailer, who doubles the price again,” he said. “So you’re buying a $4,000 product that in reality cost $1,000.” By cutting out middlemen, these millennial brands can use higher quality materials but still keep prices reasonable, he said. And they can pay shipping, often saving customers hundreds of dollars.

Even as these brands roll out bricks-and-mortar shops, the model stays intact. They favor smaller 2,000- to 4,000-square-foot showrooms as opposed to the 50,000 square-foot mazes of mainstream retailers. “Less inventory, less rent overhead...often translates into lower-cost product,” said Mr. Dillon, who opened a 3,800 square-foot store in suburban Minnesota a year after launching his site.

The condensed supply line speeds up distribution. Brooklinen can deliver its bedding within two days. Burrow sofas ship out of their North Carolina factory the same week they’re ordered, said owner Stephen Kuhl. While Pottery Barn’s site estimates its made-to-order sofas and chairs in performance velvet will take from 6 to 9 weeks, BenchMade Modern’s Los Angeles factory is currently shipping custom sofas in 21 days (up from its typical 10-days, due to holiday demand).

Pottery Barn’s brand president Marta Benson defended the chain’s turnaround. “In some cases our quote times have grown to six weeks because we have a lot of demand for our quality of upholstery,” she said. “Disrupters have the benefit of single-category focus, digital-marketing focus and a clarity of message. We’re multigenerational, multichannel, multidimensional and have a decades-old reputation.”

These new brands attempt to offset their youth by reducing buyers’ risk. Casper mattresses set the standard in 2014 when it offered free shipping on delivery and return, and offered customers 100 days to decide whether their foam mattress, shipped rolled-up in a manageable box, made them a happy sleeper. Brooklinen will exchange sheets or refund returned sheets (minus $9.99) for 365 days, no matter the reason.

If you don’t like that nonrefundable sofa you had made to order by retailers like West Elm and Crate & Barrel, you’re selling it on Craigslist or giving it to your sister. BenchMade Modern, whose sofas are customizable to the inch, pays shipping for delivery and for return within 14 days, no questions asked. “There’s some guilt with returning a $2,000 sofa,” said Mr. Blazona. “It’s OK! It’s in our business model.”

When asked if she’s heard of Casper, Brooklinen, Article or Burrow, perhaps via Instagram or Facebook , Suzann Kresse, 61, said simply, “I’m not on any of that stuff.” Yet the radiology technologist from Jefferson Township, Penn., said she’d consider buying a sofa she hasn’t sat on, given the sort of shipping and return policies these companies offer. “I work five to six days a week. If they had good pictures and I could read the specs, sure, I’d try it over going to a store. Quite frankly, who has time?”

7 ‘Millennial’ Design Brands to Know

Cutting out the middleman is as old as commerce itself. But if you’re not on social media, you likely haven’t heard of these direct-to-consumer companies shaking up the furniture industry.

The Inside

The Inside’s co-founder and CEO, Christiane Lemieux, sold her lifestyle brand DwellStudio to e-commerce behemoth Wayfair in 2013. The design tastemaker now shares her travels to places like Milan and Marrakesh with 152,000 Instagram followers as she collects vintage textiles. The Inside’s 20 different furniture styles can be made to order with more than 100 proprietary upholstery patterns. The company carries no inventory and produces each product in the U.S., like the $299 Ink Melio Screen above, in under three weeks. theinside.com

Yardbird

“We’ve worked hard to edit the outdoor-furniture industry down to the 10 designs most consumers look for,” said Yardbird co-founder Jay Dillon. The coated-aluminum bistro set below costs $1,097, including a 10-year warranty. Even with Yardbird’s 30-day trial policy for returns (charging $99 for return shipping and restocking), its return rate (excluding instances of damage) is 1%, compared to the roughly 2% average for bricks-and-mortar furniture stores, according to the Home Furnishings Association. yardbird.com

Revival

Debuting last fall with one-of-a-kind vintage and original handmade carpets from Turkey, Revival’s prices are up to 10 times lower than comparable rugs at conventional U.S. retailers. Average price of a 5-feet-by-8-feet rug? $400. “Our Turkish team works with local craftsmen to customize product in response to demand for things like soft pink tones,” said California-based co-founder and CEO Ben Hyman. The business, planning to launch a similar model in India, predicts $1.6 million in gross sales by year-end. revivalrugs.com

Dims.

The furniture brand launched in November with just four minimalist Taiwan-made tables. The pieces are designed by emerging global talents like Swede John Astbury and Korean Kyuhyung Cho, who created the ash-wood Caldera table below, $350, to help democratize the industry. The Dims. ethos includes subsidized delivery costs. “Unlike a lot of online furniture brands, we don’t pad our prices to offer ‘free shipping,’” said founder Eugene Kim. “We show how much it costs to ship a product and then pick up half the tab.” dimshome.com

BenchMade Modern

“Our sweet spot is the older millennial looking to buy something that will last,” said founder Edgar Blazona, who points to better construction and materials to justify the highish prices on his eight customizable upholstered collections. All pieces—like the Skinny Fat chair above, $1,241 including delivery—feature a zipper where the leg bolts into the frame so you can eyeball the craftsmanship. A 100-day return policy includes shipping for 14 days, a 10% handling fee thereafter. “I think we’ve gotten back one or two pieces ever,” said Mr. Blazona of the 3-year-old company. benchmademodern.com

Burrow

Founders Stephen Kuhl and Kabeer Chopra reverse-engineered Burrow’s modular furniture, available in five colors, so it could ship from their North Carolina factory in UPS boxes and be easily disassembled and moved later. “I had a big inherited sofa that needed a second person to move,” said Chicago grad student Eddy Banuelos, who bought a three-seater and ottoman like the one pictured ($1,490). Delivery is free and return shipping within a 30-day trial is covered if you’ve held on to the packaging. burrow.com

Article

Article, one of the most senior digitally native companies, was launched by four computer engineers in 2013 and has reached gross annual sales of $100 million. Its catalog of more than 2,000 modern Scandinavian, midcentury and West Coast furniture designs includes the Culla Spindle queen bed below, for $899. An ETA calculator on each product page estimates delivery time for your zip code, and a flat shipping fee of $49 covers delivery and returns within 30 days applies. “How do we do it?” reads the site. “We’re wizards. Just kidding: we’re obsessed with efficiency.” article.com

WHAT I’D NEVER, EVER BUY ONLINE / Shoppers of a Certain Age Come Clean

“I’d worry that a sofa might be uncomfortable and bad quality,” said Laurie Kantor Finn, 52, co-founder of a tech-education studio for children in Los Angeles. “Whenever I’ve bought a sofa, I’ve gone to 50 stores and sat on every one.”

“I’d want to touch and feel a piece of upholstery. Maybe If they sent fabric swatches—if I had that second tier, after a visual, of evaluating—I might do it,” said James Dale, 61, a management consultant in New York. ”But then again, I still think returning a chair or sofa would be painful. You’ve got the service elevator, etc. It’s not easy to manage.”

“I don’t buy any home furnishings online,” said over-50 Denise DeGennaro, a managing editor at a book publisher in New York. “I really like to go shopping for houseware things with my sister. It’s almost like a hobby.”

“I order a lot of things online—kitchen appliances, sheets, towels,” said Margaret Appleton, 55, an obstetrician-gynecologist from College Station, Texas. “But I wouldn’t order a mattress because I would want to lie on it. My son did get his online.”

“Sheets are so personal, and I really think you have to touch and feel them,” said Tammy Farley, a mid-50s co-founder of a hotel-consulting firm from Atlanta, Ga. “I am a hot sleeper and need percale sheets that feel crispy to keep me cool at night. I can only be sure I will like them if I can touch them.”

Corrections & Amplifications

An earlier version of this article said sofa company BenchMade Modern paid shipping for returns within 100 days. BenchMade Modern’s 100-day return policy includes shipping for 14 days, after which a 10% handling fee applies. (December 14, 2018)

An earlier version of this article incorrectly spelled La-Z-Boy. (December 14, 2018)