rigour vs harshness

rigour and harshness both are nouns.

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

As nouns, rigour and harshness are synonyms defined as:

Other synonyms of rigour include hardness, inclemency, rigor, rigorousness, rigourousness, severeness, severity, stiffness.

rigour (noun)	harshness (noun)
something hard to endure	the quality of being harsh or rough or grating to the senses
the quality of being valid and rigorous	excessive sternness
excessive sternness	the roughness of a substance that causes abrasions
	the quality of being cruel and causing tension or annoyance