You probably don't know that much about it then. Much of it is an attempt to rekindle the flame of Traditional Metal, many of the bands having felt that Thrash Metal took it too far. The only real similarity is (occasionally) the speed, pretty much everything else is different and much more aligned with regular old Heavy Metal. Attacker's first album is a perfect example of this.
Most of what I've heard has been Iced Earth clones, so that's my impression of American Power Metal. In my defense, from what I've heard/read, Iced Earth clones constitute a large portion of American power metal.