nub vs kernel

nub and kernel both are nouns.

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

As nouns, nub and kernel are synonyms defined as:

nub and kernel: the choicest or most essential or most vital part of some idea or experience

nub (noun)	kernel (noun)
the choicest or most essential or most vital part of some idea or experience	the choicest or most essential or most vital part of some idea or experience
a small piece	a single whole grain of a cereal
a small lump or protuberance	the inner and usually edible part of a seed or grain or nut or fruit stone