Metal, hard metal
Pardon my correction, but Hard Metal is not really a genre. Metal is harder than Hard Rock, Rock is obviously at the bottom. Harder than Metal would be Death Metal. And I could understand why you'd dislike that.
But yeah, the hieracrhy goes like this: Rock > Hard Rock > Metal
Each one has their own subgenres, and so are more expansive than they look. Also, far from all Metal and Rock is screamy. That's screamo and death metal - I have plenty of metal songs where the singer is wholly intelligible, and sounds just like something you might hear in something calmer.
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