folk music vs popular music

folk music and popular music both are nouns.

Word	Noun	Adjective	Verb	Adverb
folk music	Yes	No	No	No
popular music	Yes	No	No	No

As nouns, popular music is a hypernym of folk music; that is, popular music is a word with a broader meaning than folk music:

folk music: the traditional and typically anonymous music that is an expression of the life of people in a community
popular music: any genre of music having wide appeal (but usually only for a short time)

Other hypernyms of folk music include popular music genre.

folk music (noun)	popular music (noun)
the traditional and typically anonymous music that is an expression of the life of people in a community	any genre of music having wide appeal (but usually only for a short time)