celebration vs occasion

celebration and occasion both are nouns.

Word	Noun	Adjective	Verb	Adverb
celebration	Yes	No	No	No
occasion	Yes	No	Yes	No

As nouns, occasion is a hypernym of celebration; that is, occasion is a word with a broader meaning than celebration:

celebration: a joyful occasion for special festivities to mark some happy event
occasion: a formal or official social gathering or ceremony of people

Other hypernyms of celebration include affair, function, social affair, social function, social gathering, social occasion.

celebration (noun)	occasion (noun)
any joyous diversion	an event that occurs at a critical time
the public performance of a sacrament or solemn ceremony with all appropriate ritual	a formal or official social gathering or ceremony of people
a joyful occasion for special festivities to mark some happy event	a rational motive for a belief or action
	an opportunity to do something
	the time of a particular event

celebration (verb)	occasion (verb)
	give occasion to