discourtesy vs slight

discourtesy and slight both are nouns.

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

As nouns, slight is a hyponym of discourtesy; that is, slight 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
slight: a deliberate discourteous act (usually as an expression of anger or disapproval)

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

discourtesy (noun)	slight (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 expression of lack of respect

discourtesy (adjective)	slight (adjective)
	(quantifier used with mass nouns) small in quantity or degree; not much or almost none or (with `a') at least some
	lacking substance or significance
	being of delicate or slender build

discourtesy (verb)	slight (verb)
	pay no attention to, disrespect