trio vs gathering

trio and gathering both are nouns.

Word	Noun	Adjective	Verb	Adverb
trio	Yes	No	No	No
gathering	Yes	No	No	No

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

Other hypernyms of trio include assemblage.

trio (noun)	gathering (noun)
a musical composition for three performers	the social act of assembling
three people considered as a unit	the act of gathering something
a set of three similar things considered as a unit	sewing consisting of small folds or puckers made by pulling tight a thread in a line of stitching
three performers or singers who perform together	a group of persons together in one place
the cardinal number that is the sum of one and one and one