A manufacturer can separate a thick hide into three thinner hides; one is the full-grain or top-grain leather, the rest are known as "splits."
The grain is a protective surface, which binds the leather tightly, takes a finish well and provides some degree of moisture protection. Without the grain, the splits are more flexible, but less protected and less durable.
Two of the foremost leather retailers---Tandy Leather Factory and Hidecrafter Leather Company---only sell top-grain leather for upholstery purposes. Still, a couch made of split leather is an economical choice, and can provide several years of use, with proper care.
A leather-match couch may have top-grain leather on the cushions and backrests, and splits or faux-leather sides and back. This lowers the cost of the couch considerably.
Reputable leather furniture retailers will always advertise a couch as being full- or top-grain leather when they use it. Otherwise, they will simply refer to the item as a "leather couch."