Ask interior designer Elaine Griffin if she uses the word sofa or couch to describe one of the most important pieces of furniture in the living room, and you’ll get a definitive answer. “You will never hear a professional designer call an 84-inch upholstered unit with a back, two arms, and four feet anything but a sofa,” says the author of Design Rules: The Insider’s Guide to Becoming Your Own Decorator. But while “civilians tend to use the terms indistinguishably,” Elaine notes, the words have distinct definitions in history, as well as distinct uses in the home both then and now.David HillegasA tufted-back Chesterfield sofa, a popular sofa style for style and comfort since the mid-1700s. What are the Differences Between a Sofa and a Couch?The word “sofa” originates from the Arabic word suffah to describe upholstered, upright, cushioned seating with structure with two arms and a back. “Couch” comes from the French word couche, derived from the verb meaning “to lie down,” as in on a daybed.In fact, soon after Louis XIV’s death, formality among the royals in Versailles shifted to be more comfortable. “Sitting was no longer only ritualistic or functional, but became a form of relaxation,” the architect Witold Rybczynski writes in Home: A Short History of an Idea. “Women reclined on a chaise longue, which could also be used as a couch.” And yet, Witold later opined, “Writing a history of seating raises the problem of nomenclature. The Greeks and Romans dined on couches, which were really more like beds, which may be why the word derives from the French coucher, to lie down.” According to the Dictionary of Interior Design by Martin M. Peglar, the couch is defined as a lounge chair used for resting, while a sofa is an upholstered daybed or couch with arms and a back. And yet, Peglar writes, “In common usage, a couch is often confused with a sofa or settee.” Key Differences in Design Styles of Sofas and CouchesSofasOne of the earliest types of sofas—known as the Knole—first appeared during the 1600s in England. The original design featured an upright back and cantilevered, adjustable sides; it remains a classic piece that’s been reinterpreted with now stationary tall arms that lean out on either side.Alec HemerA Knole-style sofa in a traditional living roomSkirted sofas are flirty and fun. But sofas can also be “a little serious and buttoned up, more tailored and pristine,” says Minneapolis interior designer Lucy Penfield. “We feel compelled to hold on to a sofa, like an heirloom.”From cottage country to tailored traditional, sofas can take on myriad personalities depending on how they’re shaped and dressed. “Arm shape, back and seat cushion details, and body length are all design elements that contribute to the style statement, and that’s before the fabric goes on,” Elaine says. She adds that English roll arm sofas are more formal, while straight or “track arms” (whether wide or narrow) are more modern. “There’s a time and a room for them all,” she says.Rachel Whiting An English roll arm sofa in a cottage-style living roomElaine also notes the latest sofa trends are stepping away from basic beige even though they are often an investment piece meant to last for years. “I’m seeing all-over florals, geometrics, and nature-inspired patterns along with added details such as fringe and other embellishments. The bolder, the better,” she says.CouchesCouches, on the other hand, connote comfort, snuggling with a pet, and kicking back after a long day. “Feet up and comfortable, nothing precious—a couch is like a cowboy and a rugged old friend,” Penfield says. California interior designer Marynn Udvarhelyi, owner of Wildflower Home Interiors, agrees. “Couches can and are beautiful, but the priority is comfort for TV and movie watching, game nights, snacking, and napping.”For modernists, Ludwig Mies van der Rohe’s Barcelona Couch, a low-profile tufted daybed with no back or arms and a cylindric bolster pillow at one end, is a timeless piece that serves both sitting and lounging. The legendary architect designed the piece in 1930, but the couch still is in production today through Knoll.ShutterWorx//Getty ImagesA Barcelona CouchMore on Sofas (Or Couches, If You Prefer)What’s Right For Your Space “A sofa belongs in the formal or front living room, sitting room, end of bed, or library because it only needs to seat occasional visitors or members of the household who are using it for conversation, reading, or working from home,” Marynn says. Read McKendree for Country LivingDesigner Marynn Udvarhelyi sourced a gingham check sofa for her client’s cottage on Cape Cod.Due to their comfy connotation, couches are more common in casual parts of the home, such as family rooms, media rooms, and basements, the sizes can vary to take up more space. Larger sectionals and modular couches are also popular for versatility and to accommodate larger or smaller groups of people.Start Shopping:How Important Is It to Know the Difference?“Couch seems to have prevailed; we say ‘casting couch’ and ‘couch potato,’ and psychiatrists have couches, not sofas,” Witold Rybczynski writes. “Sofas seem to be more domestic, which may be why a couch that converts into a bed is called a sleeper sofa or a sofa bed. Go figure.”Designers admit it that while the two terms might inevitably be intertwined, the pros should know better. “Only the most discerning homeowners will even notice the usage of sofa versus couch,” Marynn says. “But for an interior designer, always using the proper term helps command respect and a working knowledge of the (often very expensive) products they are using in a client’s home.” For Elaine, that lesson came early in her career, when she used the term couch while talking to the head of furniture design at Peter Marino Architect. “He snapped back, ‘It’s a sofa! We do NOT say couch!’” she recalls. “Needless to say, I was mortified.”More Sofa and Couch Inspiration:Kelly Ryan KegansKelly Ryan Kegans is a Minneapolis-based writer, editor, and photo stylist with more than 25 years of experience producing home design content for brands including Country Living, Better Homes & Gardens, and HGTV Magazine. Her own home is populated with more books than shelves, a few too many scrubbed pine tables, and moody photos of gray day landscapes, which are her happy place.