sternness vs hardship

sternness and hardship both are nouns.

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

As nouns, hardship is a hypernym of sternness; that is, hardship is a word with a broader meaning than sternness:

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

sternness (noun)	hardship (noun)
uncompromising resolution	something hard to endure
the quality (as of scenery) being grim and gloomy and forbidding	something that causes or entails suffering
	a state of misfortune or affliction