octet vs musical group

octet and musical group both are nouns.

Word	Noun	Adjective	Verb	Adverb
octet	Yes	No	No	No
musical group	Yes	No	No	No

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

Other hypernyms of octet include musical organisation, musical organization.

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