cub vs male child

cub and male child both are nouns.

Word	Noun	Adjective	Verb	Adverb
cub	Yes	No	Yes	No
male child	Yes	No	No	No

As nouns, male child is a hypernym of cub; that is, male child is a word with a broader meaning than cub:

Other hypernyms of cub include boy.

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

cub (verb)	male child (verb)
give birth to cubs