Read the post that guy is posting. Its an awesome guide to metal genres. Plus, you'll find great bands you might have not heard about
:
http://www.magle.dk/music-forums/929...ed-thanks.html
Your best bet is to listen to it. Look, death metal and power metal are on completely opposing sides of the spectrum. SO be thankful you asked your questions here instead of a metal forum haha People are nasty on the internet (look at my own posts lol)
This is an invaluable site: metal-archives.com Click search by genre, go to death metal and power metal, visit the bands's myspace's (theres a link on the bands's metal archive page), and come back here. Once you listen to it, rather than read descriptions, you are gonna understand. Probably hit yourself in the head for being confused about it.
Whoever gave you the confusion to thinking Amon Amarth was power should be shot. Dont worry, Ill help you track him down.