Vocals are the weakest link in genre classification; any style of vocals can be used in any other style of metal, other than what they were originally used in the context of. There is black metal with death vocals (newer Deathspell Omega), death metal with black vocals (fucking plenty I won't bother to name), power metal with harsh vocals (Children Of Bodom), etc. I have never heard death metal with all clean vocals, but that's probably just happenstance.
Themes are there to get you thinking, though in metal they're usually nothing of interest nowadays: basically just something for you to pay secondary attention to so you don't get bored or whatever.
cookiecutter said:
If some metalcore band began singing about gore and put a mutilated body on the cover of an album, they may begin to be labelled deathcore or something similar.
The Black Dahlia Murder sometimes sing about graves, zombies, ghouls, etc. They're nothing but melo-death/metalcore, though. Not deathcore or goregrind or whatever else you wanna pigeonhole 'em as. Themes do not play a part in deciding genre classification.
The Greys said:
The only reason to me bands are called 'melodic death metal' is because the carcass -heartwork style raspy vocals. Musically these bands sound like a mix between iron maiden and judas priest. I like some of the melodic death metal bands and there would probably be no other way to label them anyways,.
A valid and correct point; In Flames and a lot of the more commercialized and degraded melo-death bands are just 80's metal with "random harsh vocals"...death metal is defined by:
1. a strong, driving rhythm section with emphasis on bass and non-linear patterns
2. heavy, chromatic guitar riffs; very downtuned
3. narrative structures wherein the point is not to drive home a few verses, a repetitive chorus, and a solo or lead section of some kind
Once you realize that these things are prevalent in almost every death metal band to ever exist, you'll know why we use the genre classification system and why death metal bands are death metal. There should be a separation between melo-death (Swedish style melody combined with early heavy metal riff structures/song structures, and harsh vocals) and MELODIC DEATH METAL (bands who primarily belong to death metal but utilize traditional harmony within their music to a rather great extent).