Woodchuck or Groundhog?

When people talk about a varmint in their yard, along with rabbits, voles, field mice, and gophers, the groundhog or woodchuck usually shows up. Same or different?

groundhog - woodchuck - whistlepig

As it turns out, a woodchuck is a groundhog, and is also called a whistlepig. They are in the Marmot, or ground squirrel family.

So, how much wood would a woodchuck chuck, if a woodchuck could chuck wood?
A woodchuck would chuck just as much wood as a groundhog would hog ground, if a groundhog could hog ground.
And a groundhog would hog just as much ground as a whistlepig would pig whistles, if a whistlepig could pig whistles.