ensemble vs musical group

ensemble and musical group both are nouns.

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

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

Other hypernyms of ensemble include musical organisation, musical organization.

ensemble (noun)	musical group (noun)
a coordinated outfit (set of clothing)	an organization of musicians who perform together
the chorus of a ballet company
a group of musicians playing or singing together
an assemblage of parts or details (as in a work of art) considered as forming a whole
a cast other than the principals