plant substance vs cork

plant substance and cork both are nouns.

Word	Noun	Adjective	Verb	Adverb
plant substance	Yes	No	No	No
cork	Yes	No	Yes	No

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

Other hyponyms of plant substance include cutin, chaff, husk, shuck, stalk, straw, stubble, plant product, vegetable tallow, wood.

plant substance (noun)	cork (noun)
material derived from plants	the plug in the mouth of a bottle (especially a wine bottle)
	a small float usually made of cork; attached to a fishing line
	outer bark of the cork oak; used for stoppers for bottles etc.
	(botany) outer tissue of bark; a protective layer of dead cells

plant substance (verb)	cork (verb)
	stuff with cork
	close a bottle with a cork