plant part vs kernel

plant part and kernel both are nouns.

Word	Noun	Adjective	Verb	Adverb
plant part	Yes	No	No	No
kernel	Yes	No	No	No

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

plant part: any part of a plant or fungus
kernel: the inner and usually edible part of a seed or grain or nut or fruit stone

plant part (noun)	kernel (noun)
any part of a plant or fungus	the choicest or most essential or most vital part of some idea or experience
	a single whole grain of a cereal
	the inner and usually edible part of a seed or grain or nut or fruit stone