I have been a heavy metal fan for as long as I remember, but not until recent investigations did I learn there were so many subgenres of metal, as well as what sets all these genres apart. I have found nearly 40 subgenres of heavy metal! I will briefly explain the characteristics of a few more notable metal styles.
Classic Heavy Metal: characterized by mid-to-fast-tempo riffs, by thumping basslines, crunchy riffs, extended guitar solos, and clean, often high-pitched vocals and anthemic choruses. It is not generally categorized as a subgenre of metal, but the main genre of it. Examples include Black Sabbath, Judas Priest, and Iron Maiden.
Death Metal: characterized by the use of heavily distorted guitars, harsh vocals that are low-pitched or growled, dark and morbid lyrics, exceptionally fast-paced rhythms and melodies, frequent blast beats on drums, and complex song structures with multiple tempo changes. Examples include Possessed, Obituary, Morbid Angel, and Cannibal Corpse.
Black Metal: employs fast tempos, both shrieked vocals and low-pitched growled vocals are used, highly distorted guitars played with tremolo picking in sometimes droning or hypnotic patterns, and unconventional song structure. Lyrical themes opposing Christianity are heavily used. It places more emphasis on creating a specific atmosphere of dread or depression than death metal or thrash metal. Corpse paint is worn during performances. Examples include Mayhem, Gorgoroth, Immortal, and Behemoth
Power Metal: emphasizes clean, melodic, high-pitched vocals, fast pacing that is mostly driven by double bass drumming and melodic lead guitar. Sometimes, screamed vocals or gang vocals are used, but usually only as backing vocals. Power metal leans toward the positive side of life, seeking to empower the listener and inspire joy and courage. Power metal lyrics usually involve fantasy or science fiction themes. Examples include Stratovarious, Helloween, Dragonforce, and Kamelot
Thrash Metal: characterized by its fast tempos, complexity and aggression. Thrash metal guitar playing is most notable for the “chugging” sound it creates through low-pitched palm muted riffs, and high-pitched shred guitar solos. Drummers often use double-bass drumming. Vocals are most often shouted or sung in an aggressive manner. Examples include Metallica, Slayer, Anthrax, Megadeth, and Pantera.