ceremony vs occasion

ceremony and occasion both are nouns.

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

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

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

ceremony (noun)	occasion (noun)
the proper or conventional behavior on some solemn occasion	an event that occurs at a critical time
any activity that is performed in an especially solemn elaborate or formal way	a formal or official social gathering or ceremony of people
a formal event performed on a special occasion	a rational motive for a belief or action
	an opportunity to do something
	the time of a particular event

ceremony (verb)	occasion (verb)
	give occasion to