plant part vs lobe

plant part and lobe both are nouns.

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

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

plant part (noun)	lobe (noun)
any part of a plant or fungus	a rounded projection that is part of a larger structure
	(anatomy) a somewhat rounded subdivision of a bodily organ or part
	the enhanced response of an antenna in a given direction as indicated by a loop in its radiation pattern
	(botany) a part into which a leaf is divided