sixth vs musical interval

sixth and musical interval both are nouns.

Word	Noun	Adjective	Verb	Adverb
sixth	Yes	Yes	No	No
musical interval	Yes	No	No	No

As nouns, musical interval is a hypernym of sixth; that is, musical interval is a word with a broader meaning than sixth:

sixth: the musical interval between one note and another six notes away from it
musical interval: the difference in pitch between two notes

Other hypernyms of sixth include interval.

sixth (noun)	musical interval (noun)
the musical interval between one note and another six notes away from it	the difference in pitch between two notes
one part in six equal parts
position six in a countable series of things

sixth (adjective)	musical interval (adjective)
coming next after the fifth and just before the seventh in position