The first thing that might come to mind is that practice and rehearsal are really one and the same thing, but they actually are not. When one is practicing they are engaging in the process of developing their own personal confidence and competence on their particular instrument of choice.
When one rehearses they usually aren’t doing so by themselves, but with other musicians in a group, band or orchestra setting, which is where all the players work together with each one playing their assigned parts of chosen pieces of music or songs within the set list.
It should be noted that in either setting there needs to be minimal to no interruption whatsoever because the player(s) need to be able to fully concentrate on the task at hand, which is either practicing or rehearsing.
Like anything else, you will only get out of music what you are willing to put into it, so the more practicing an individual does, the more they’re going to get out of music, and the more a group of musicians rehearses together the more cohesive they will become.