keynote vs musical note

keynote and musical note both are nouns.

Word	Noun	Adjective	Verb	Adverb
keynote	Yes	No	Yes	No
musical note	Yes	No	No	No

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

keynote: (music) the first note of a diatonic scale
musical note: a notation representing the pitch and duration of a musical sound

Other hypernyms of keynote include note, tone.

keynote (noun)	musical note (noun)
a fundamental or central idea	a notation representing the pitch and duration of a musical sound
(music) the first note of a diatonic scale
the principal theme in a speech or literary work

keynote (verb)	musical note (verb)
set the keynote of
give the keynote address to (an audience)