A Dire wolf is larger than a grey/timber wolf and has both bite and claw as an attack, like a Warg.
A normal wolf just has a bite attack.
A Warg, is sort of like an undead wolf, but does not have any of the normal properties of undead. It can still be stunned and it can bleed ect. When it dies, the body goes away in a greasy black puff of smoke and soot on the wind.......