musical organisation vs musical group

musical organisation and musical group both are nouns.

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

As nouns, musical organisation and musical group are synonyms defined as:

musical organisation and musical group: an organization of musicians who perform together

Other synonyms of musical organisation include musical organization.

musical organisation (noun)	musical group (noun)
an organization of musicians who perform together	an organization of musicians who perform together