sextet vs musical organisation

sextet and musical organisation both are nouns.

Word	Noun	Adjective	Verb	Adverb
sextet	Yes	No	No	No
musical organisation	Yes	No	No	No

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

Other hypernyms of sextet include musical group, musical organization.

sextet (noun)	musical organisation (noun)
a musical composition written for six performers	an organization of musicians who perform together
six people considered as a unit
a set of six similar things considered as a unit
six performers or singers who perform together
the cardinal number that is the sum of five and one