Ondatra zibethica vs gnawer

Ondatra zibethica and gnawer both are nouns.

Word	Noun	Adjective	Verb	Adverb
Ondatra zibethica	Yes	No	No	No
gnawer	Yes	No	No	No

As nouns, gnawer is a hypernym of Ondatra zibethica; that is, gnawer is a word with a broader meaning than Ondatra zibethica:

Ondatra zibethica: beaver-like aquatic rodent of North America with dark glossy brown fur
gnawer: relatively small placental mammals having a single pair of constantly growing incisor teeth specialized for gnawing

Other hypernyms of Ondatra zibethica include rodent.

Ondatra zibethica (noun)	gnawer (noun)
beaver-like aquatic rodent of North America with dark glossy brown fur	relatively small placental mammals having a single pair of constantly growing incisor teeth specialized for gnawing