This question originated from the larger question here about returning aggressive serves. So
Is the footwork in the volley-returning serve the same as in the basic volley near the net?
This is a subtle question because it depends - as everything else in tennis - what kind of ball you have to deal with and what you aim to do with it.
Human beings - i.e not Federer - typically block serves with the sole aim of getting the ball back in play, preferably with some depth. Often enough, height is not a crucial factor as long as the ball isn't a total floater. In light of this, the typical footwork for blocking service returns is somewhat docile in practice: most players do not shift their bodyweight forward nor bend their knees very much.
A typical volley, on the other hand, is hit under very different circumstances and with very different purpose. First of all, they are mostly hit while moving forward, which already determines a lot of the footwork. Second, they are mostly hit close to the net with the ball dropping sharply, so the knees must be bent much more than when returning serve. Lastly, it is often essential to keep your volleys low so as not to give your opponent time and space to generate reasonable pace. But this requires much more purposeful footwork, comprised of many small adjustments to control your center of gravity and momentum.