quartet vs musical composition

quartet and musical composition both are nouns.

Word	Noun	Adjective	Verb	Adverb
quartet	Yes	No	No	No
musical composition	Yes	No	No	No

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

Other hypernyms of quartet include composition, opus, piece, piece of music.

quartet (noun)	musical composition (noun)
a musical composition for four performers	a musical work that has been created
four people considered as a unit
a set of four similar things considered as a unit
four performers or singers who perform together
the cardinal number that is the sum of three and one