ruefulness vs regret

ruefulness and regret both are nouns.

Word	Noun	Adjective	Verb	Adverb
ruefulness	Yes	No	No	No
regret	Yes	No	Yes	No

As nouns, ruefulness and regret are synonyms defined as:

ruefulness and regret: sadness associated with some wrong done or some disappointment

Other synonyms of ruefulness include rue, sorrow.

ruefulness (noun)	regret (noun)
sadness associated with some wrong done or some disappointment	sadness associated with some wrong done or some disappointment

ruefulness (verb)	regret (verb)
	decline formally or politely
	express with regret
	feel remorse for; feel sorry for; be contrite about
	feel sad about the loss or absence of