pocket gopher vs pocket rat

pocket gopher and pocket rat both are nouns.

Word	Noun	Adjective	Verb	Adverb
pocket gopher	Yes	No	No	No
pocket rat	Yes	No	No	No

As nouns, pocket rat is a hypernym of pocket gopher; that is, pocket rat is a word with a broader meaning than pocket gopher:

pocket gopher: burrowing rodent of the family Geomyidae having large external cheek pouches; of Central America and southwestern North America
pocket rat: any of various rodents with cheek pouches

pocket gopher (noun)	pocket rat (noun)
burrowing rodent of the family Geomyidae having large external cheek pouches; of Central America and southwestern North America	any of various rodents with cheek pouches