callosity vs hardness

callosity and hardness both are nouns.

Word	Noun	Adjective	Verb	Adverb
callosity	Yes	No	No	No
hardness	Yes	No	No	No

As nouns, callosity and hardness are synonyms defined as:

Other synonyms of callosity include callousness, insensibility, unfeelingness.

callosity (noun)	hardness (noun)
devoid of passion or feeling; hardheartedness	a quality of water that contains dissolved mineral salts that prevent soap from lathering
an area of skin that is thick or hard from continual pressure or friction (as the sole of the foot)	the property of being rigid and resistant to pressure; not easily scratched; measured on Mohs scale
	the quality of being difficult to do
	devoid of passion or feeling; hardheartedness
	excessive sternness