Panthera pardus vs big cat

Panthera pardus and big cat both are nouns.

Word	Noun	Adjective	Verb	Adverb
Panthera pardus	Yes	No	No	No
big cat	Yes	No	No	No

As nouns, big cat is a hypernym of Panthera pardus; that is, big cat is a word with a broader meaning than Panthera pardus:

Panthera pardus: large feline of African and Asian forests usually having a tawny coat with black spots
big cat: any of several large cats typically able to roar and living in the wild

Other hypernyms of Panthera pardus include cat.

Panthera pardus (noun)	big cat (noun)
large feline of African and Asian forests usually having a tawny coat with black spots	any of several large cats typically able to roar and living in the wild