come back vs repay

come back and repay both are verbs.

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

As verbs, come back and repay are synonyms defined as:

Other synonyms of come back include rejoin, retort, return, riposte.

come back (verb)	repay (verb)
be restored	answer back
go back to something earlier	pay back
answer back	make repayment for or return something
even the score, in sports	act or give recompense in recognition of someone's behavior or actions