pika vs gnawing mammal

pika and gnawing mammal both are nouns.

Word	Noun	Adjective	Verb	Adverb
pika	Yes	No	No	No
gnawing mammal	Yes	No	No	No

As nouns, gnawing mammal is a hypernym of pika; that is, gnawing mammal is a word with a broader meaning than pika:

pika: small short-eared burrowing mammal of rocky uplands of Asia and western North America
gnawing mammal: relative large gnawing animals; distinguished from rodents by having two pairs of upper incisors specialized for gnawing

Other hypernyms of pika include lagomorph.

pika (noun)	gnawing mammal (noun)
small short-eared burrowing mammal of rocky uplands of Asia and western North America	relative large gnawing animals; distinguished from rodents by having two pairs of upper incisors specialized for gnawing