First off: Metal is NOT a type of rock. Metal is a whole style of music in and of itself.

Also, black metal is VERY different from death and gothic metal. I'd post how they are but I know I have done it so much as of late I have grown tired of it.

So to teach you how you will listen to:

Death - Human (death metal)

and

Emperor - In The Nightside Eclipse (black metal)

and

Beseech - Souls Highway (Gothic metal)

to tell the differences.