kernel vs quiddity

kernel and quiddity both are nouns.

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

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

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

Other hyponyms of kernel include bare bones, hypostasis, haecceity, quintessence, stuff.

kernel (noun)	quiddity (noun)
the choicest or most essential or most vital part of some idea or experience	the essence that makes something the kind of thing it is and makes it different from any other
a single whole grain of a cereal	an evasion of the point of an argument by raising irrelevant distinctions or objections
the inner and usually edible part of a seed or grain or nut or fruit stone