Momentum is conserved in both elastic and perfectly inelastic collisions.
In an elastic collision, the total momentum of the colliding objects is conserved before and after the collision. This means that the sum of the momentum of the objects before the collision is equal to the sum of the momentum of the objects after the collision.
In a perfectly inelastic collision, the two objects stick together after the collision, forming a single object with new momentum. In this case, the total momentum of the system is also conserved.
However, in an inelastic collision, momentum is not conserved, as some of the momenta are transformed into other forms of energy, such as heat or sound. This means that the total momentum of the objects before the collision is not equal to the total momentum of the objects after the collision.