Elastic Collision: If the kinetic energy of the system is conserved during a collision, it is called an elastic collision. The total kinetic energy before the collision and after collision remains unchanged. The collision between subatomic particles is generally elastic. The collision between two steel or glass balls is nearly elastic. In elastic collision, the linear momentum and kinetic energy of the system are conserved.
Inelastic collision: During a collision between two bodies if there is a loss of kinetic energy, then the collision is said to be an inelastic collision. Since there is always some loss of kinetic energy in any collision, collisions are generally inelastic. In inelastic collision, the linear momentum is conserved but the energy is not conserved. If two bodies stick together. after colliding, the collision is perfectly inelastic but it is a special case of inelastic collision called plastic collision.