photo op vs social gathering

photo op and social gathering both are nouns.

Word	Noun	Adjective	Verb	Adverb
photo op	Yes	No	No	No
social gathering	Yes	No	No	No

As nouns, social gathering is a hypernym of photo op; that is, social gathering is a word with a broader meaning than photo op:

photo op: an occasion that lends itself to (or is deliberately arranged for) taking photographs that provide favorable publicity for those who are photographed
social gathering: a formal or official social gathering or ceremony of people

Other hypernyms of photo op include affair, function, occasion, social affair, social function, social occasion.

photo op (noun)	social gathering (noun)
an occasion that lends itself to (or is deliberately arranged for) taking photographs that provide favorable publicity for those who are photographed	a formal or official social gathering or ceremony of people