musician vs instrumentalist

musician and instrumentalist both are nouns.

Word	Noun	Adjective	Verb	Adverb
musician	Yes	No	No	No
instrumentalist	Yes	No	No	No

As nouns, musician and instrumentalist are synonyms defined as:

Other synonyms of musician include player.

musician (noun)	instrumentalist (noun)
artist who composes or conducts music as a profession	someone who plays a music as a profession
someone who plays a music as a profession