social affair vs social occasion

social affair and social occasion both are nouns.

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

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

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

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

social affair (noun)	social occasion (noun)
a formal or official social gathering or ceremony of people	a formal or official social gathering or ceremony of people