opportunity vs possibility

opportunity and possibility both are nouns.

Word	Noun	Adjective	Verb	Adverb
opportunity	Yes	No	No	No
possibility	Yes	No	No	No

As nouns, possibility is a hypernym of opportunity; that is, possibility is a word with a broader meaning than opportunity:

Other hypernyms of opportunity include possibleness.

opportunity (noun)	possibility (noun)
a possibility due to a favorable combination of circumstances	a tentative insight into the natural world; a concept that is not yet verified but that if true would explain certain facts or phenomena
	a possible alternative
	a future prospect or potential
	capability of existing or happening or being true