go back vs come back

go back and come back both are verbs.

Word	Noun	Adjective	Verb	Adverb
go back	No	No	Yes	No
come back	No	No	Yes	No

As verbs, come back is a hypernym of go back; that is, come back is a word with a broader meaning than go back:

Other hypernyms of go back include hark back, recall, return.

go back (verb)	come back (verb)
regain a former condition after a financial loss	be restored
return in thought or speech to something	go back to something earlier
belong to an earlier time	answer back
	even the score, in sports