Gophers
Larger and heavier than gophers. Gophers' teeth are yellow even when their mouths are closed, but groundhogs' are white.
Marmot
Marmots look like giant groundhogs. Marmots are smaller and have more colourful fur than groundhogs. Marmots aren't as common as groundhogs in the US.
Badger
Mistaken groundhog and badger burrows. Both have short legs and big bodies. Despite resemblance, badgers and groundhogs are separate.
Prairie dogs
The groundhogs & prairie dogs are Marmotini family members. They have comparable body shapes and similar-colored fur. Groundhog is bigger.
Beavers
Groundhogs dwell in underground burrows, but beavers need water nearby. The beavers devour trees and other woody plants.
Squirrels
Groundhogs are brown or grey like squirrels. Groundhogs and squirrels eat similar foods. They're bigger than squirrels.
Capybaras
They're like groundhogs. Both have hair and big front teeth. Capybaras are bigger and rarer than groundhogs. Capybaras are South American.
Chipmunks
Chipmunks and groundhogs aren't often confused. Despite appearances, chipmunks and groundhogs are alike. Both Sciuridae and diggers.
Voles
Voles dig tunnels and burrows like groundhogs. Voles have a similar body structure to groundhogs and eat the same plants and grasses.