singer vs musician

singer and musician both are nouns.

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

As nouns, musician is a hypernym of singer; that is, musician is a word with a broader meaning than singer:

Other hypernyms of singer include instrumentalist, player.

singer (noun)	musician (noun)
a person who sings	artist who composes or conducts music as a profession
	someone who plays a music as a profession