Panthera leo vs lioness

Panthera leo and lioness both are nouns.

Word	Noun	Adjective	Verb	Adverb
Panthera leo	Yes	No	No	No
lioness	Yes	No	No	No

As nouns, lioness is a hyponym of Panthera leo; that is, lioness is a word with a more specific, narrower meaning than Panthera leo:

Panthera leo: large gregarious predatory feline of Africa and India having a tawny coat with a shaggy mane in the male
lioness: a female lion

Other hyponyms of Panthera leo include lion cub, lionet.

Panthera leo (noun)	lioness (noun)
large gregarious predatory feline of Africa and India having a tawny coat with a shaggy mane in the male	a female lion