reject vs rebuff

reject and rebuff both are nouns.

Word	Noun	Adjective	Verb	Adverb
reject	Yes	No	Yes	No
rebuff	Yes	No	Yes	No

As verbs, rebuff is a hyponym of reject; that is, rebuff is a word with a more specific, narrower meaning than reject:

Other hyponyms of reject include repel, snub.

reject (noun)	rebuff (noun)
the person or thing that is rejected or set aside as inferior in quality	a deliberate discourteous act (usually as an expression of anger or disapproval)
	an instance of driving away or warding off

reject (verb)	rebuff (verb)
not accept something given or offered	reject outright and bluntly
dismiss from consideration or a contest	force or drive back
deem wrong or inappropriate
reject with contempt
not accept as true
refuse entrance or membership
resist immunologically the introduction of some foreign tissue or organ