corkwood tree vs shrub

corkwood tree and shrub both are nouns.

Word	Noun	Adjective	Verb	Adverb
corkwood tree	Yes	No	No	No
shrub	Yes	No	No	No

As nouns, shrub is a hypernym of corkwood tree; that is, shrub is a word with a broader meaning than corkwood tree:

corkwood tree: very small deciduous dioecious tree or shrub of damp habitats in southeastern United States having extremely light wood
shrub: a low woody perennial plant usually having several major stems

Other hypernyms of corkwood tree include bush.

corkwood tree (noun)	shrub (noun)
very small deciduous dioecious tree or shrub of damp habitats in southeastern United States having extremely light wood	a low woody perennial plant usually having several major stems