quartet vs gathering

quartet and gathering both are nouns.

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

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

Other hypernyms of quartet include assemblage.

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