ceremonial occasion vs affair

ceremonial occasion and affair both are nouns.

Word	Noun	Adjective	Verb	Adverb
ceremonial occasion	Yes	No	No	No
affair	Yes	No	No	No

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

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

ceremonial occasion (noun)	affair (noun)
a formal event performed on a special occasion	a vaguely specified concern
	a formal or official social gathering or ceremony of people
	a usually secretive or illicit sexual relationship