operatic star vs vocalizer

operatic star and vocalizer both are nouns.

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

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

Other hypernyms of operatic star include singer, vocaliser, vocalist.

operatic star (noun)	vocalizer (noun)
singer of lead role in an opera	a person who sings
	an organism that can utter vocal sounds