rigorousness vs hardship

rigorousness and hardship both are nouns.

Word	Noun	Adjective	Verb	Adverb
rigorousness	Yes	No	No	No
hardship	Yes	No	No	No

As nouns, rigorousness and hardship are synonyms defined as:

Other synonyms of rigorousness include asperity, grimness, rigor, rigour, rigourousness, severeness, severity.

rigorousness (noun)	hardship (noun)
something hard to endure	something hard to endure
excessive sternness	something that causes or entails suffering
	a state of misfortune or affliction