How do you know the music is pop or rock?

Answer 1

If the musicians play their own instruments, if the focus isn't entirely on the vocals and if it sounds like rock... then it's probably rock. Sorry, that probably wasn't too helpful but it's the best I can do.

Answer 2

It's not always easy to tell just by listening, since a number of artists have paid tribute to a certain era by imitating the style of that time. There are certainly some performers during the 1980s who became popular for a particular style: in hard rock, there were a number of bands whose lead singers had long, often professionally-styled hair, and these groups were jokingly called "Hair Bands" or "Hair Metal Bands"-- they included Bon Jovi, Guns 'n' Roses, Winger, Whitesnake, and Poison. But the decade was not just hard rock, of course. A number of other genres were popular on the charts too.

Probably the best way to tell whether a song is considered 80s pop is to go to a publication like Billboard and look at the top 100 charts for the 1980s. I enclose a link to a site that lists the number one hit songs, according to Billboard, from each year of the 1980s. There are also other sites which list the top ten from each year.