The second means that he started playing the piano at the age of 7 and he still plays the piano (probably on a fairly regular basis).
There is a little ambiguity and the second could mean that he has been playing the piano constantly (without stopping) since the age of 7. He would be very tired by now!! It is very unlikely that anyone would think that was true so you don't need to worry about that ambiguity but I just thought I would draw your attention to it.
Student or Learner