How do you tell genres apart?

Answer 1

the vocal timbre of the instruments and voice is most prominent. Then would be the chord progressions in their music. Tempo can also sometimes be a huge contributer. There are a handful of bands that have set the groundwork for each genre. If you juxtapose modern bands with a few of these profound groundbreaking bands, you can see how almost all music is referencing a few of these bands.

Answer 2

In music, it's pretty easy to overlap genres. Taylor Swift, for example, is a country-pop crossover. She uses a rock and roll beat and less twang than straight Country Music, but she also relies on typical country music instruments and song topics.

In movies and books, it's a little harder. However, a classic example is The Princess Bride because it uses witty humor, romance, and adventure. It can't be categorized as a comedy, chick-flick, or action film because it uses a little bit of each.

A general rule: take a few characteristics of each genre you are combining and put them together, you'll be in the overlap.