My understanding is that *strength* comes back quicker. This enables mass to come back quicker, but the causation is reversed. A lot of strength is neuromuscular control over muscle, not muscle mass itself. So it doesn't take as long for the relevant brain neurons to remember how to more efficiently recruit the muscle mass that's there.

This is a similar effect to how one sees all the time a leaner, wiry person be stronger than a more muscular, pumped person.