overlap vs coincidence

overlap and coincidence both are nouns.

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

As nouns, coincidence is a hypernym of overlap; that is, coincidence is a word with a broader meaning than overlap:

Other hypernyms of overlap include co-occurrence, concurrence, conjunction.

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

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