coincidence vs overlap

coincidence and overlap both are nouns.

Word	Noun	Adjective	Verb	Adverb
coincidence	Yes	No	No	No
overlap	Yes	No	Yes	No

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

Other hyponyms of coincidence include concomitance, contemporaneity, contemporaneousness, unison.

coincidence (noun)	overlap (noun)
the temporal property of two things happening at the same time	a flap that lies over another part
the quality of occupying the same position or area in space	the property of partial coincidence in time
an event that might have been arranged although it was really accidental	a representation of common ground between theories or phenomena

coincidence (verb)	overlap (verb)
	extend over and cover a part of
	coincide partially or wholly