cub vs give birth

cub is a noun but give birth is not a noun.

Word	Noun	Adjective	Verb	Adverb
cub	Yes	No	Yes	No
give birth	No	No	Yes	No

As verbs, give birth is a hypernym of cub; that is, give birth is a word with a broader meaning than cub:

Other hypernyms of cub include bear, birth, deliver, have.

cub (noun)	give birth (noun)
the young of certain carnivorous mammals such as the bear or wolf or lion
a male child (a familiar term of address to a boy)
an awkward and inexperienced youth

cub (verb)	give birth (verb)
give birth to cubs	cause to be born
	create or produce an idea