observance vs social gathering

observance and social gathering both are nouns.

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

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

observance: a formal event performed on a special occasion
social gathering: a formal or official social gathering or ceremony of people

Other hypernyms of observance include affair, function, occasion, social affair, social function, social occasion.

observance (noun)	social gathering (noun)
the act of observing; taking a patient look	a formal or official social gathering or ceremony of people
conformity with law or custom or practice etc.
the act of noticing or paying attention
a formal event performed on a special occasion