What is the difference between particle velocity and wave velocity of a simple harmonic progressive wave?

I encountered these words regarding reflection of simple harmonic progressive wave.
In detail, it was written,"...Consider a crest of a transverse wave of a string incident normally on on a wall. As crest cannot travel further, wave velocity is reversed. Now, the particle of the wall at which the crest is incident is not free to vibrate. Therefore, reflection takes place in such a way that the particle velocity is also reversed. Reversal of particle velocity causes a change of phase of pi rad. Hence, crest is reflected as trough..."
Such explanations are given regarding troughs, and also longitudinal waves.

Are these velocities i.e. particle velocity and wave velocity, different from each other?
What are they actually?

Please explain.

Thank you!