validity vs rigour

validity and rigour both are nouns.

Word	Noun	Adjective	Verb	Adverb
validity	Yes	No	No	No
rigour	Yes	No	No	No

As nouns, validity and rigour are synonyms defined as:

Other synonyms of validity include cogency, rigor.

validity (noun)	rigour (noun)
the quality of having legal force or effectiveness	something hard to endure
the quality of being valid and rigorous	the quality of being valid and rigorous
	excessive sternness