dullness vs boringness

dullness and boringness both are nouns.

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

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

dullness (noun)	boringness (noun)
lack of sensibility	extreme dullness; lacking spirit or interest
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