Suppose two particles are colliding. Let initial velocities be $u_1$ and $u_2$ .Their final velocities are $v_1$ and $v_2$. Now $u_1$ and $u_2$ are known. By intuition I can understand that $v_1$ and $v_2$ will depend on the coefficient of restituition and hence on their material.
Now I have an equation from conservation of linear momentum and another for the coefficient of restituition. I can now find $v_1$ and $v_2$. So it looks as if $v_1$ and $v_2$ depend upon the coefficient only.
But in my physics textbook I have a solved problem. There, a ball hits a wall and initial and final velocities and the mass of the ball were given. They have basically calculated the average force and impulse. They are saying that the impulse remains same and the maximum force along with the time of collision will depend on the softness or hardness of the ball.
But that means we have the same $v_1$ and $v_2$ for different coefficients of restituition. So where is my thinking wrong?