Is there a diffrence between old wotlk and new wotlk

I just whant to know if there is diffrence between old wotlk and new one if there diffrence in server and players.
I instaled old version and when i searach for players it says only 50 found, but on forum it says there is 7000 players for icecrown.

old and new are the same, only on the new one your character looks a bit better like they upgraded it during warlords of draenor.
you can play the old client or the new one.
if you search for players ingame through the /who function it only shows you 50 players, its by design, but there are actual 7000 players playing