comeback vs backtalk

comeback and backtalk both are nouns.

Word	Noun	Adjective	Verb	Adverb
comeback	Yes	No	No	No
backtalk	Yes	No	No	No

As nouns, backtalk is a hyponym of comeback; that is, backtalk 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)
backtalk: an impudent or insolent rejoinder

Other hyponyms of comeback include back talk, lip, mouth, sass, sassing.

comeback (noun)	backtalk (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)