Black Metal
 

What is it??? How is it different from hardcore, screamcore, or heavy metal???

I have attempted to find those very same answers. It appears, each fan has their own justifications for the labels.
Black metal, as explained to me, is when the main subject matter is darkness, Satan, blashphemy.

hahaha screamcore...

anyway, it's metal. But it's metal with pretty crap production usually. That usually turns people off. The riffs more often than not rely on dissonance rather than straight power chords. Often quite bizarre melodic ideas are used, and the emphasis (on the good stuff anyway) is on creating this abysmal nasty atmosphere. It's quite amazing stuff, though absolutely it's an aquired taste.

Yeah it's kind of hard to explain because even the black metal genre is divided, between the more commercial black metal bands (Dimmu Borgir, Cradle of Filth, Emperor), and the lo-fi raw sounding stuff like Burzum and old Mayhem, Dark Funeral... yeah...

The more popular style of black metal usually has heavy keyboards and symphonic elements, vocals are usually high pitched screaming unlike most death metal or metalcore where the screaming is lower pitched... guitars are usually technical with a lot of scandinavian and maiden sounding influence sometimes, a lot of the "buzzsaw" riffing in minor scales that's common in death metal, lots of blast drum beats...

Most of the older black metal, the raw low-fi sounding stuff, isn't nearly as well produced and has much simpler song structures and simpler riffs. Lots of power chords and steady drum beats that almost resemble punk sometimes... Vocals are usually high pitched screaming (standard in black metal), occasional blast beats but not nearly as much as the more popular, commercial black metal. Lots of "buzzsaw" in minor scales like popular black metal also.

This is, at least, my interpretation of the genre... feel free to correct me where I might be wrong

whoa whoa.... you're not listening to the right tr00 black metal if you're hearing simple riffs and structures... :p it's not at ALL simpler than the "commercial" side stuff. Maybe the oldest stuff like burzum and darkthrone is, but not anything in the last 5 years that's any good in black metal. Weakling and Deathspell Omega come to mind, that;s fuckign complex music that's "true" black metal. I suggest you take another look at some of the stuff that's out there. hehe.

Yeah... I haven't really kept up to date in the underground black metal since I quit the band I was in (being in a death metal band, you get a lot of obscure shit thrown at you), but I'm sure it's gotten better since I stopped keeping up with it... actually I'm sure there was better stuff even when I was keeping up with it, just not exposed to it. But yeah, I didn't mean what I said in a derogatory manner, I love all metal except the stuff that sucks. (and I'm pretty lenient)

here its a similar question i asked

and a website that was posted that clarified the metal genres

I can almost never get to the Wikipedia pages, their servers are overloaded or something. However, the same information is crossposted at Answers.com:
List of heavy metal genres: Information From Answers.com
black metal: Information From Answers.com

Anyone wanting the last word on Black metal should get their hands on issues 127-129 (February-April) of Terrorizer. There is a incredible three part special devoted to the origins, evolution, key recordings and every other aspect of black metal.
In fact if you having any interest in extreme metal a subscription to Terrorizer is vital, nothing else comes close to it.