h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I don't know if retorting is a real word or not but...

Death Metal - this actually started as a hybrid from thrash metal and at it's inception often covered areas of morality (Death's - Spiritual Healing for example was a rage against mothers who gave birth to drug addicted children, people who don't add value in life, "spiritual" healing itself and other topics). It is distinguished by gruff vocals as a general rule but "clean" vocals are beginning to make a breakthrough as well.

Black Metal - Venom, Bathory etc. were probably not Satanic in nature but the first wave of "real black metal" was very definitely satanic. Bands such as Mayhem, Burzum, Darkthrone etc. were heavily satanic and it has to be said it wasn't just imagery - church burnings, murder, homophilia, homophobia and racism were all related to this core set of beliefs which were differently interpreted among the scene's main members. Current black metal still has it's satanic element but nihilism, atheism and pagnism definitely have their place within the scene now. And oddly enough early black metal was very similar to death metal due to the fact that Euronymous (of Mayhem - and very much considered to be the founding father of "real black metal") created the scene in protest at the image of death metal not at it's music - the sound itself evolved later (as can be seen by listening to the evolution of sound from early Darkthrone, Immortal, Mayhem etc.)

Personally I think it's a shame that any of the "subscenes" are only given a two line explanation here as they all have full and different cultures and historys even White/Christian Metal which is still sadly musically unblessed.