Unfortunately, I don't have a pic of a Butternut fruit, but it's lemon-shaped rather that spherical like the Black Walnut.
The range of the plants are about the same, although Butternut is shifted a bit more north than the walnut.
It is much, much less common than walnut. It's not common anywhere in its range. It's a rather short-lived tree, only lasting about 75 years at the most.
This plant was photographed at a local university, IPFW, which has a very cool Tree Walk. I could probably do a whole blog just about all of the trees that have been planted on its campus. If you're a tree guy and get to Fort Wayne, you need to check this out.