rusticity vs stiffness

rusticity and stiffness both are nouns.

Word	Noun	Adjective	Verb	Adverb
rusticity	Yes	No	No	No
stiffness	Yes	No	No	No

As nouns, stiffness is a hypernym of rusticity; that is, stiffness is a word with a broader meaning than rusticity:

rusticity: the quality of being rustic or gauche
stiffness: the inelegance of someone stiff and unrelaxed (as by embarrassment)

Other hypernyms of rusticity include awkwardness, clumsiness, gracelessness.

rusticity (noun)	stiffness (noun)
the quality of being rustic or gauche	the physical property of being inflexible and hard to bend
	the property of moving with pain or difficulty
	the inelegance of someone stiff and unrelaxed (as by embarrassment)
	excessive sternness
	firm resoluteness in purpose or opinion or action