Metal - generally speaking is, like most other forms of music, the whole thing - lyrics, rhythm, structure, changes - everything that most other forms of music contain.
Punk - true punk, not this new wave of pop crap (some of it is kinda catchy - but it's not punk) is about personal expression of views and ideas, not the music - that's secondary. Some punk bands are very good musicians and play very well, but for most punk bands the "music" is merely a vehicle to broadcast the message.
Apples and oranges.
D.
