hardness vs callosity

hardness and callosity both are nouns.

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

As nouns, hardness and callosity are synonyms defined as:

Other synonyms of hardness include callousness, insensibility, unfeelingness.

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