Well, first of all, punk and emo/goth are not the same thing. Avenged Sevenfold, Megadeath, and Falloutboy are TOTALLY different from good stuff like Dead Kennedys, Bad Religion, and the Ramones(:
The styles, therefore, are different too. For instance, people who go to punk concerts like DK concerts are there to mosh and don't care about how their hair looks, so they'll just be anarchists and go with whatever. Punk curls would probably be more tussled and messy. Trust me, I've been to some of those concerts, haha. Take Nancy (Sid and Nancy of the Sex Pistols) for instance. Here are punk curls:
As you can see, Courtney Love has got that messy thing going on ^
Emo, I'm guessing, would be more clean cut...curly hair and straight, long bangs. http://www.emobucket.com/albums/user...normal_gh8.jpg
I guess it just depends on what look you're aiming for. HTH!