concurrence vs unison

concurrence and unison both are nouns.

Word	Noun	Adjective	Verb	Adverb
concurrence	Yes	No	No	No
unison	Yes	No	No	No

As nouns, unison is a hyponym of concurrence; that is, unison is a word with a more specific, narrower meaning than concurrence:

Other hyponyms of concurrence include concomitance, overlap, contemporaneity, contemporaneousness.

concurrence (noun)	unison (noun)
acting together, as agents or circumstances or events	(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
agreement of results or opinions	corresponding exactly
a state of cooperation