social occasion vs social gathering

social occasion and social gathering both are nouns.

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

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

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

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

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