callousness vs dullness

callousness and dullness both are nouns.

Word	Noun	Adjective	Verb	Adverb
callousness	Yes	No	No	No
dullness	Yes	No	No	No

As nouns, dullness is a hyponym of callousness; that is, dullness is a word with a more specific, narrower meaning than callousness:

callousness (noun)	dullness (noun)
devoid of passion or feeling; hardheartedness	lack of sensibility
	without sharpness or clearness of edge or point
	the quality of lacking interestingness
	a lack of visual brightness
	the quality of being slow to understand