comeback vs back talk

comeback and back talk both are nouns.

Word	Noun	Adjective	Verb	Adverb
comeback	Yes	No	No	No
back talk	Yes	No	No	No

As nouns, back talk is a hyponym of comeback; that is, back talk is a word with a more specific, narrower meaning than comeback:

comeback: a quick reply to a question or remark (especially a witty or critical one)
back talk: an impudent or insolent rejoinder

Other hyponyms of comeback include backtalk, lip, mouth, sass, sassing.

comeback (noun)	back talk (noun)
return by a celebrity to some previously successful activity	an impudent or insolent rejoinder
a quick reply to a question or remark (especially a witty or critical one)