unison vs co-occurrence

unison and co-occurrence both are nouns.

Word	Noun	Adjective	Verb	Adverb
unison	Yes	No	No	No
co-occurrence	Yes	No	No	No

As nouns, co-occurrence is a hypernym of unison; that is, co-occurrence is a word with a broader meaning than unison:

unison: occurring together or simultaneously
co-occurrence: the temporal property of two things happening at the same time

Other hypernyms of unison include coincidence, concurrence, conjunction.

unison (noun)	co-occurrence (noun)
(music) two or more sounds or tones at the same pitch or in octaves	the temporal property of two things happening at the same time
occurring together or simultaneously	an event or situation that happens at the same time as or in connection with another
corresponding exactly