quiddity vs nub

quiddity and nub both are nouns.

Word	Noun	Adjective	Verb	Adverb
quiddity	Yes	No	No	No
nub	Yes	No	No	No

As nouns, nub is a hypernym of quiddity; that is, nub is a word with a broader meaning than quiddity:

quiddity: the essence that makes something the kind of thing it is and makes it different from any other
nub: the choicest or most essential or most vital part of some idea or experience

quiddity (noun)	nub (noun)
the essence that makes something the kind of thing it is and makes it different from any other	the choicest or most essential or most vital part of some idea or experience
an evasion of the point of an argument by raising irrelevant distinctions or objections	a small piece
	a small lump or protuberance