musician vs arranger

musician and arranger both are nouns.

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

As nouns, arranger is a hyponym of musician; that is, arranger is a word with a more specific, narrower meaning than musician:

musician: artist who composes or conducts music as a profession
arranger: a musician who adapts a composition for particular voices or instruments or for another style of performance

musician (noun)	arranger (noun)
artist who composes or conducts music as a profession	a person who brings order and organization to an enterprise
someone who plays a music as a profession	a musician who adapts a composition for particular voices or instruments or for another style of performance