Mostly inelastic. In real life none is 100% of one or the other. However, in real life there are but a few collisions where the two bodies rebound off each other. Car wrecks for example are clearly inelastic for the most part.

Games like pool are the more common case where the collision are nearly perfectly elastic. But even here some energy is lost in the collisions. How do I know? I can hear the sound of them colliding and that’s energy lost from the rebound.