What is rock? What is metal?
 

What are the characteristics that define the two music forms? In my experience its not metal unless the lead singer is growling.

It's true there are a lot of forms of metal where growling is the norm, but there are also quite a few others where the singing is almost operatic. So I don't think that's the best way of classifying metal.

What is mettal? What is rock?

i don't know how you would really sum the two up. rock is a vast genre with many different sub genres. metal depends on a few factors too and has all it's own sub-genres too. to me it's the whole sound that makes it metal. that depends on era to. i've seen motley crue, poison, whitesnake, etc. classified as metal but i wouldn't consider it metal at all.

some of the things, in my opinion anyways, that make music metal is that a lot of the time metal bands will use a drop tuning to make it deeper, thicker, more eerie, loud type sound. a lot of bass double kicking on the drums is used as well. it more or less has a thicker, heavier sound than the majority of rock bands.

every one has a differing opinions on what's metal though. you might say a band is metal where i would say it was more rock so there really is easy way to class it. again i think the time it was produced plays a big factor because a lot of old "metal" would be considered hard rock by today's standards as metal has evolved into heavier and faster beats today. don't know if this helps at all.

devildriver, system of a down, black sabbath, the agonist, the agony scene, megadeth - metal

godsmack, papa roach, nickelback, ac/dc - rock

Metal is also directly descended from rock so a lot of metal is really just a subgenre of the gigantic umbrella genre that is rock. It's only when you start talking about a band like Sunn 0))) that I think you're talking about a type of metal that isn't rock.

Let me put in two cents and see what y'all think. I thought that mettal bands typically used a faster paced music where the electric gitar was more in the forefornt of the music where as in rock the electric gitars are more simply a member of the band rather than the dominant member. The music tends to disapear into the gitars. In rock the instruments tend to be more of equal members of the band.

Nope. Guitar is often the dominant instrument in both. Listen to Chuck Berry, Dick Dale or Jimi Hendrix and you can hear just how dominant the guitar can be in rock.

The difference between rock and metal is the emotions they elicit, IMO, hard to define

It's more like you know metal when you hear it, and you know rock when you hear it.