torch singer vs vocalizer

torch singer and vocalizer both are nouns.

Word	Noun	Adjective	Verb	Adverb
torch singer	Yes	No	No	No
vocalizer	Yes	No	No	No

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

torch singer: a singer (usually a woman) who specializes in singing torch songs
vocalizer: a person who sings

Other hypernyms of torch singer include singer, vocaliser, vocalist.

torch singer (noun)	vocalizer (noun)
a singer (usually a woman) who specializes in singing torch songs	a person who sings
	an organism that can utter vocal sounds