new player

what the different btw old and new version of wotlk server ?

go here: https://www.warmane.com/download and get "Wotlk (old)"

i can play in ICECROWN x7 with old version ?

It's not about the server, you can play on any WOTLK realm with either (old) or new client.
New one looks a bit better but crashes more often.