discourtesy vs rebuff

discourtesy and rebuff both are nouns.

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

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

discourtesy: a lack of politeness; a failure to show regard for others; wounding the feelings of others
rebuff: a deliberate discourteous act (usually as an expression of anger or disapproval)

Other hyponyms of discourtesy include derision, ridicule, indelicacy, insolence, affront, insult, presumption, slight.

discourtesy (noun)	rebuff (noun)
a lack of politeness; a failure to show regard for others; wounding the feelings of others	a deliberate discourteous act (usually as an expression of anger or disapproval)
a manner that is rude and insulting	an instance of driving away or warding off
an expression of lack of respect

discourtesy (verb)	rebuff (verb)
	reject outright and bluntly
	force or drive back