torch singer vs singer

torch singer and singer both are nouns.

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

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

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

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

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