squirrel vs gnawer

squirrel and gnawer both are nouns.

Word	Noun	Adjective	Verb	Adverb
squirrel	Yes	No	No	No
gnawer	Yes	No	No	No

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

squirrel: a kind of arboreal rodent having a long bushy tail
gnawer: relatively small placental mammals having a single pair of constantly growing incisor teeth specialized for gnawing

Other hypernyms of squirrel include rodent.

squirrel (noun)	gnawer (noun)
a kind of arboreal rodent having a long bushy tail	relatively small placental mammals having a single pair of constantly growing incisor teeth specialized for gnawing
the fur of a squirrel