coincidence vs chance event

coincidence and chance event both are nouns.

Word	Noun	Adjective	Verb	Adverb
coincidence	Yes	No	No	No
chance event	Yes	No	No	No

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

coincidence: an event that might have been arranged although it was really accidental
chance event: anything that happens suddenly or by chance without an apparent cause

Other hypernyms of coincidence include accident, fortuity, stroke.

coincidence (noun)	chance event (noun)
the temporal property of two things happening at the same time	anything that happens suddenly or by chance without an apparent cause
the quality of occupying the same position or area in space
an event that might have been arranged although it was really accidental