what is the physical difference between claws and hooves?
A nail is homologous to a claw but is flatter and has a curved edge instead of a point. A nail that is big enough to bear weight is called a "hoof". (Nevertheless, one side of the cloven-hoof of artiodactyl ungulates may also be called a claw). Every so often, the growth of claws stops and restarts, as does hair.