lioness vs Panthera leo

lioness and Panthera leo both are nouns.

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

As nouns, Panthera leo is a hypernym of lioness; that is, Panthera leo is a word with a broader meaning than lioness:

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

Other hypernyms of lioness include king of beasts, lion.

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