concomitant vs co-occurrence

concomitant and co-occurrence both are nouns.

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

As nouns, concomitant and co-occurrence are synonyms defined as:

concomitant and co-occurrence: an event or situation that happens at the same time as or in connection with another

Other synonyms of concomitant include accompaniment, attendant.

concomitant (noun)	co-occurrence (noun)
an event or situation that happens at the same time as or in connection with another	the temporal property of two things happening at the same time
	an event or situation that happens at the same time as or in connection with another

concomitant (adjective)	co-occurrence (adjective)
occurring with or following as a consequence