Hides have to be split into two layers before they can be used as furniture leather. The bottom layer created by that split is referred to as split leather or sometimes as bottom grain.
The top portion of the hide is called "top-grain leather" and has a more compact grain than the split leather. Top-grain leather is more suitable for furniture upholstery, although some upholsterers use split leather to cover the back of a leather sofa in order to keep costs down. Split leather is more likely to be found in such items as the leather work gloves sold at hardware stores.