cub vs lion cub

cub and lion cub both are nouns.

Word	Noun	Adjective	Verb	Adverb
cub	Yes	No	Yes	No
lion cub	Yes	No	No	No

As nouns, lion cub is a hyponym of cub; that is, lion cub is a word with a more specific, narrower meaning than cub:

cub: the young of certain carnivorous mammals such as the bear or wolf or lion
lion cub: a young lion

Other hyponyms of cub include bear cub, tiger cub.

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

cub (verb)	lion cub (verb)
give birth to cubs