waltz vs dance music

waltz and dance music both are nouns.

Word	Noun	Adjective	Verb	Adverb
waltz	Yes	No	Yes	No
dance music	Yes	No	No	No

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

waltz (noun)	dance music (noun)
a ballroom dance in triple time with a strong accent on the first beat	music to dance to
music composed in triple time for waltzing	a genre of popular music composed for ballroom dancing
an assured victory (especially in an election)

waltz (verb)	dance music (verb)
dance a waltz