rock star vs vocalizer

rock star and vocalizer both are nouns.

Word	Noun	Adjective	Verb	Adverb
rock star	Yes	No	No	No
vocalizer	Yes	No	No	No

As nouns, vocalizer is a hypernym of rock star; that is, vocalizer is a word with a broader meaning than rock star:

Other hypernyms of rock star include rock 'n' roll musician, rocker, singer, vocaliser, vocalist.

rock star (noun)	vocalizer (noun)
a famous singer of rock music	a person who sings
	an organism that can utter vocal sounds