cork vs stop up

cork is a noun but stop up is not a noun.

Word	Noun	Adjective	Verb	Adverb
cork	Yes	No	Yes	No
stop up	No	No	Yes	No

As verbs, stop up is a hypernym of cork; that is, stop up is a word with a broader meaning than cork:

Other hypernyms of cork include plug, secure.

cork (noun)	stop up (noun)
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

cork (verb)	stop up (verb)
stuff with cork	fill or close tightly with or as if with a plug
close a bottle with a cork