social function vs affair

social function and affair both are nouns.

Word	Noun	Adjective	Verb	Adverb
social function	Yes	No	No	No
affair	Yes	No	No	No

As nouns, social function and affair are synonyms defined as:

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

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

social function (noun)	affair (noun)
a formal or official social gathering or ceremony of people	a vaguely specified concern
	a formal or official social gathering or ceremony of people
	a usually secretive or illicit sexual relationship