An elastic collision occurs when the sum of the kinetic energy of a moving object is equal to the sum of the kinetic energy of the object after collision with another object.
An inelastic collision occurs when there is a change in the sum of kinetic energies before and after the object has collided with another object.
An inelastic collision between two solid masses at the same speed, both solids collide and bounce off of each other without losing their speed.
In an inelastic collision between two solids at the same speed, the final speed of one of the objects becomes greater than the final speed of the other object.
In an elastic collision, there is no deformation of either of the colliding bodies. For instance, snooker balls colliding on a pool table.
In an inelastic collision, one or both of the colliding bodies suffers a deformation. For example, a collision between two speeding cars.