affair vs ceremony

affair and ceremony both are nouns.

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

As nouns, ceremony is a hyponym of affair; that is, ceremony is a word with a more specific, narrower meaning than affair:

affair (noun)	ceremony (noun)
a vaguely specified concern	the proper or conventional behavior on some solemn occasion
a formal or official social gathering or ceremony of people	any activity that is performed in an especially solemn elaborate or formal way
a usually secretive or illicit sexual relationship	a formal event performed on a special occasion