Is rock music like heavy metal?

they are both very similar

There are some smiliarities between rock and the lightest metal types. But trve metal is nothing like rock at all. Vocal styles, drum styles, guitar styles, bass styles all change. Also rock music is usually way better funded because there is a lower level of musicianship and a higher level of demand in it. Mainly because the vast majority of people are idiotic and prefer simplistic musical styles.

Listen to Breaking Benjamin and then listen to bands like Mayhem, Burzum, Opeth and such to get an idea of what I mean.