No, I'm not going to compare the two bands, album for album (I like doing that with Megadeth and Metallica because Megadeth always comes out on top). I would like to point out some differences that might make you a fan of one or the other--or both. Amon Amarth is viking metal. When you listen to "Oden" it feels like you are embroiled in a battle against a worthy opponent with blood and guts flying all around. There are no resting points the music and message is clear: Pure Unfettered Toughness.
Opeth takes the unbridled aggression and mixes it with melody and a softer sound. The riffs keep coming until you feel like you can't take anymore and then they move to hauntingly melodic passages that allow you to exhale.
I'm a fan of both bands but the musician (prog-nerd) that lives inside me is a bigger fan of Opeth. That being said, I'm excited for the AA show coming up in December. I've got some preparatory tasks that you should try to complete before the show--in order to embrace the true meaning of Viking Metal:
1. Go see the new Beowulf!!!! Great movie, looks real most of the time.
2. Rent the 13th Warrior (or read The Eater's of the Dead)
3. Rent Pathfinder. Underrated movie that shows a frightening portrayal of Viking life.
4. Eat some mutton (or at least a turkey leg or two) with fresh bread and thick gravy.
5. Listen to "With Oden On Our Side" 23 times.
6. Brew and drink your own Mead
