debater vs rebutter

debater and rebutter both are nouns.

Word	Noun	Adjective	Verb	Adverb
debater	Yes	No	No	No
rebutter	Yes	No	No	No

As nouns, rebutter is a hyponym of debater; that is, rebutter is a word with a more specific, narrower meaning than debater:

debater: someone who engages in debate
rebutter: a debater who refutes or disproves by offering contrary evidence or argument

Other hyponyms of debater include devil's advocate, confuter, disprover, refuter, wrangler.

debater (noun)	rebutter (noun)
someone who engages in debate	(law) a pleading by the defendant in reply to a plaintiff's surrejoinder
	a debater who refutes or disproves by offering contrary evidence or argument