music genre vs musical genre

music genre and musical genre both are nouns.

Word	Noun	Adjective	Verb	Adverb
music genre	Yes	No	No	No
musical genre	Yes	No	No	No

As nouns, music genre and musical genre are synonyms defined as:

Other synonyms of music genre include musical style.

music genre (noun)	musical genre (noun)
an expressive style of music	an expressive style of music