I know that restitution determines the bounciness of a body - zero means no bouncy at all, one means 100% bouncy without any energy lost in the normals direction (Is that right?)
With restitution, the energy is first converted to what I think is called elastic potential, where the objects squish together, and then after that it is converted back into kinetic energy. The coefficient of restitution determines how much kinetic energy is lost to sound or whatever, and then that remaining energy is split in half between the two objects (unless one is static, in which case the mobile one gets all the remaining energy).