lioness vs king of beasts

lioness and king of beasts both are nouns.

Word	Noun	Adjective	Verb	Adverb
lioness	Yes	No	No	No
king of beasts	Yes	No	No	No

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

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

Other hypernyms of lioness include lion, Panthera leo.

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