Most often associated with larger animals - the leather when removed from the hide of an animal is extremely thick and the first thing done is to split the leather cross-sectionally, into layers. The bottom layer is made into "split-leather." Split leather is further broken down into two categories - side and shoulder. Side split is the most durable and best quality but also the most expensive. Shoulder split is also quite durable but slightly more economical. Belly split is the most economical and least durable cut.
This is the top layer. It has a more appealing appearance and hence more expensive than split-leather. It is better for outdoor working conditions and is very durable.
The hide can come from several different places, resulting in different qualities and uses. Top grain is the highest quality and lasts the longest, followed by split leather.