imperiousness vs arrogance

imperiousness and arrogance both are nouns.

Word	Noun	Adjective	Verb	Adverb
imperiousness	Yes	No	No	No
arrogance	Yes	No	No	No

As nouns, arrogance is a hypernym of imperiousness; that is, arrogance is a word with a broader meaning than imperiousness:

imperiousness: the trait of being imperious and overbearing
arrogance: overbearing pride evidenced by a superior manner toward inferiors

Other hypernyms of imperiousness include haughtiness, hauteur, high-handedness, lordliness.

imperiousness (noun)	arrogance (noun)
the trait of being imperious and overbearing	overbearing pride evidenced by a superior manner toward inferiors