affair vs occasion

affair and occasion both are nouns.

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

As nouns, affair and occasion are synonyms defined as:

affair and occasion: a formal or official social gathering or ceremony of people

Other synonyms of affair include function, social affair, social function, social gathering, social occasion.

affair (noun)	occasion (noun)
a vaguely specified concern	an event that occurs at a critical time
a formal or official social gathering or ceremony of people	a formal or official social gathering or ceremony of people
a usually secretive or illicit sexual relationship	a rational motive for a belief or action
	an opportunity to do something
	the time of a particular event

affair (verb)	occasion (verb)
	give occasion to