hey, man. on a 510 atty, i'm assuming the extreme is a low resistance which means as brian say - lots more vapor...
the down side of that is it can burn off flavor and depending upon the juice you could end up with more vapor, hotter vapor, but less flavor...
if you're a flavor head, looking for a smoother experience, look for 510 attys in the 2.0-2.4 ohm range...