Heavy metal : tempo and beat of drums does not sound fast. Use high pitch clean vocals. Mostly the band in this genre starts in 80s.
Bands for the following for this genre : Manowar, Accept
Thrash Metal : aggresive drums, tight riffs and guitars, Energetic vocals. Sometimes shrieking nearly like BM vocals. The golden era was around in middle 80s. For themes they use can be politics, facts of life, propaganda, rants and more
Bands for the following for this subgenre : Slayer, Sodom, Testament, early Metallica and Megadeth, Havok, Lost society, Evile etc
> Death metal : sometimes uses repetitive patterns of drums but sometimes not really fast. Simple riffs and old school sounds. They use GROWL vocals technique. [remember.. GROWL and SCREAM are far different]. For themes , sometimes anything from fantasy, death, gore, even darkness and more. Bands for the following for this genre : Bolt Thrower, Immolation, Dismember etc.
~ progressive death metal : more complex musically. You can blend it with jazz elements, technical elements. Most of bands uses CLEAN vocals.
For the following bands : Opeth, Ne Obliviscaris, Haken, Gojira, Noneuclid
Fleshgod Apocalypse, Nile, Obscura etc
Black metal : repetitive drums [identically with repetitive drums, tremolo picking and blast beats] Uses harsh , shrieks, and fry vocals technique. for themes, mostly its Satanic [Black metal known as satanic when this subgenre first ever invented in late 80s,because its basically anti-religion music. BUT times has change and more innovative also more creative. So NOT ALL Black metal bands are satanic] , the themes they tell about are Darkness, nature, Winter, Fantasy, Ghost tales, satanic and more.
There are many kinds of Black metal subgenres :
For the following bands for this subgenre : [early] darkthrone and mayhem, Skagganauk abyss, Warwulf, Satanic Warmaster, Sargeist, Behexen, (old stuff from) Dimmu Borgir, Immortal, Taake,Marduk, Astarte, Dark Funeral,Taake and more
~ Melodic black metal : have melodic and melancholy guitar sounds. So melodic and up beat. Sometimes also have atmospheric elements.
For the following bands : Dissection, Thulcandra, Dark Fortress, Frozen Dawn, Dawn and more
(Dark Fortress, german black metal)
For the following bands : Grand Alchemist, Carach Angren, Neron Kaisar and some late stuff of Dimmu borgir and more
(Carach Angren, Dutch symphonic black metal)
~ Progressive black metal : more complex musically. Just its black metal with the touch of clean vocals in certain parts. For all i've discovered it also have atmospheric -ish.
For the following bands : Enslaved, Shylmagoghnar, Amiensus etc
Viking metal : actually Viking is just the theme in the music. Since any genre could fitting as it's a matter of sense of the theme.
For the following bands : Caladan Brood, Summoning, Kråke, Veldes, Raventale etc
Folk/celtic Metal : metal with elements of traditional instruments. Mostly related with Ancient stories , viking and pagan. Can be sounded in melodic death metal music kinds and even black metal also power metal.
For the following bands : Eluveitie, Skilltron [Folk power metal], Equilibrium, Korpiklaani, Northland, Stribog, Krampus etc
More subgenres to come
Doom metal.. Doom metal is a subgenre that have slow beat, simple and plain riffs. Themes they use are such as sadness, pain etc. whether melodic or not its still be called just doom metal.
For the following bands : Akelei, Draconian, My Dying Bride etc
-Post -Metal / rock : its subgenre that a half metal or rock. Especially for post metal.. Mostly you will hear touch of guitar ambience. There are very few kinds but im just going to tell you 3 subgenres [that i usually listen, which i actually more understand]
> Shoegaze : lots of guitar ambience, softer music. Soft kind of metal.
Bands for the following : New stuff of Alcest, Les Discrets, Ameseours etc
> Post Black Metal : one of unique subgenres.. The music itself sounds a half black metal and half metal. So the music is also slow but still have blast beats and repetitive drums in certain parts. But slower music and relaxing. Sometimes classic guitars also included as their instrument.. So its more like classic relaxing kind of music
Bands for the following : old stuff from Alcest, Agalloch, Oak Pantheon etc
(Agalloch)
Oriental metal : this term usually used for bands that have middle eastern music influence. For all i've discovered bands like Orphaned Land and Myrath are definitely in this category.
As for black metal, Melechesh, Darkestrah etc
Blackened death metal : faster and heavier sound from the drums. With black metal influence too. They use growl and shrieks vocal techniques.
For the following bands like : Behemoth, Hate etc
Avant-Garde metal : experimental metal. In its music it probably wont hear any typical metal you use to listen. Thats why its called avant-garde. Bands for the following is, band like Thy Catafalque are categorized as this.
There are alot of avant-garde black metal but so far they are recommended to try Diabolical Masquerade also for the example
Symphonic metal : sometimes sounds like gothic metal, power metal and also can be sounds like opera. Vocals tech uses clean vocals. Mostly female as the vocalist. But basically.Its a matter of vocal they use actually. For the following bands : Nightwish, Epica, Leaves' eye.