lion vs lion cub

lion and lion cub both are nouns.

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

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

lion: large gregarious predatory feline of Africa and India having a tawny coat with a shaggy mane in the male
lion cub: a young lion

Other hyponyms of lion include lioness, lionet.

lion (noun)	lion cub (noun)
large gregarious predatory feline of Africa and India having a tawny coat with a shaggy mane in the male	a young lion
a celebrity who is lionized (much sought after)