WotLK I want to play as Warlock but is there any difference about the race?

[Karlack]

I mean, I want to play as Gnomo because is fun, but humans have the abbilitie do escape from stuns, so when rogues come after you, you can just escape one time and it could be enough, you can use trinkets but...
Well, it makes a big difference?

[Overloard99]

Human > a free stun escape racial which means you can use 2 trinkets for pvp, no need for alliace medallion, thus better dps.
Gnomes > they get intellect boost which stacks

So if you want pvp > human.