subduedness vs dullness

subduedness and dullness both are nouns.

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

As nouns, dullness is a hypernym of subduedness; that is, dullness is a word with a broader meaning than subduedness:

subduedness: the property of lights or sounds that lack brilliance or are reduced in intensity
dullness: a lack of visual brightness

subduedness (noun)	dullness (noun)
the property of lights or sounds that lack brilliance or are reduced in intensity	lack of sensibility
a disposition to be patient and long suffering	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