instance vs happening

instance and happening both are nouns.

Word	Noun	Adjective	Verb	Adverb
instance	Yes	No	Yes	No
happening	Yes	No	No	No

As nouns, happening is a hypernym of instance; that is, happening is a word with a broader meaning than instance:

Other hypernyms of instance include natural event, occurrence, occurrent.

instance (noun)	happening (noun)
an item of information that is typical of a class or group	an event that happens
an occurrence of something

instance (verb)	happening (verb)
clarify by giving an example of