hardihood vs hardiness

hardihood and hardiness both are nouns.

Word	Noun	Adjective	Verb	Adverb
hardihood	Yes	No	No	No
hardiness	Yes	No	No	No

As nouns, hardihood and hardiness are synonyms defined as:

hardihood and hardiness: the trait of being willing to undertake things that involve risk or danger

Other synonyms of hardihood include boldness, daring.

hardihood (noun)	hardiness (noun)
the trait of being willing to undertake things that involve risk or danger	the property of being strong and healthy in constitution
	the trait of being willing to undertake things that involve risk or danger