Depending on the animal, you can split, or skive, a hide into several layers, usually 2 or 3. The first layer, the top grain, is harder than the layer or layers closer to the inside. In making a layered tip you can take, say 8, layers from the same batch and have more consistency, than a single layer tip. I am sure compression is a factor in the creation of all tips, layered or single. Both styles will have their own unique characteristics and fans.
In answer to your question, the layers of split hides are separated into groups of cell density, or hardness, and the tips are made from selections of these groups.
This construction is used in creating other leather products as well.