I wouldn't classify all these bands as "metal". Some are just "hard rock". And just when you think you have it sorted out, someone comes along to blur the lines, which is how subgenres get created. And the subgenres of each class are almost too much to keep track of. And the names of some of these subgenres....hair metal, glam metal, speed metal, thrash metal, doom metal....are misnomers; as they aren't really "metal", but subgenres of "hard rock". These subgenres tend to describe a bands appearance, moreso than their musical stylings, IMO.
In very broad and general terms, at its basic premise, blues is the basis for hard rock, while classical music is the basis for metal. Generally speaking, hard rock tends to be lighter in nature/content, happier, optimistic...a "celebration" of something; while metal tends to be darker in nature/content, discontented, and somewhat pessimistic. Hard rock tends to be about a "self" experience, while metal tends to be about a larger societal experience or issue. As a result, hard rock musicians place a higher priority on partying and getting laid; while metal musicians place a higher priority on musical talent and instrumental proficiency.
We're painting in very broad strokes here, and there are exceptions to every rule. If the above criteria were a checklist, we're looking for the "overall fit", as very few bands are going to fit 100% entirely within a classification. And it is somewhat objective, subject to individual interpretation. But in my opinion, many of the bands on that list are "hard rock" bands, not metal bands. Here are my outlooks on each listed band:
- Metallica - metal band, no argument whatsoever
- Black Sabbath - a metal band in most respects, but music is blues-based, not classical-based; i'll still give 'em the nod for fitting most other criteria though, which is why they're the fathers of heavy metal, before classical influences defined it
Guns N Roses - a hard rock band all the way; no metal here- Pantera - a good blend of hard rock & heavy metal; music is a combo of blues & classical bases; I'd give 'em the nod to metal though
- Sound Garden (I think they are metal) - I can't comment...not really familiar with them
- System of the Down - only heard a few tunes, but what I heard is classical-infused; metal band
Rush - constantly evolving; no 2 albums sound the same; by definition a "progressive rock" band; not metalLed Zeppelin - heavily blues based; the fathers of hard rock genre, not metal- Anthrax - another solid metal band
- Iron Maiden - a good mix of blues and classical influences, but overall presentation of metal
- Megadeth - a solid metal band with obvious classical nuances in nearly every tune
- Slayer - metal
- Dream Theater - seems to fit most criteria as metal...."progressive metal"; what Rush would sound like if Rush were metal?!
Judas Priest - often referenced as metal, and embrace the moniker; but a blues-based hard rock band all the way (my favorite on this list, but not metal)- Ozzy - which version of Ozzy? Rhandy Rhoads era, sure! Jake E. Lee era, maybe. Zakk Wylde era...Zakk is a blues guitarist with classical influences. I guess I'd give him the nod to metal, but his band has constantly shifted & evolved. And Ozzy doesn't write music...or even all his own lyrics. But it's almost always dark. Only Ozzy could take a lovely ballad with Lita Ford and make it about death...."Close Your Eyes Forever"
ACDC - ain't nothing metal about AC/DC; quintessential hard rock band!
Of course, these are all just my opinion. Subject to interpretation by others, as well!
