opus vs musical composition

opus and musical composition both are nouns.

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

As nouns, opus and musical composition are synonyms defined as:

Other synonyms of opus include composition, piece, piece of music.

opus (noun)	musical composition (noun)
a musical work that has been created	a musical work that has been created