A:
The Ultimate is more of a winter/snow boot than the Classic: sturdier construction, an extra band of suede around the toes and heel, a heavier, thicker sole with better traction, and lined with thicker fleece to keep feet warm even at -20 degrees F! The removable fleece insole does have a built-in arch support, but it's not huge (which is a good thing for me, with my almost-flat feet). If you need a higher arch than the insole provides, you could always buy a shoe insert and put it in the boot under the fleece insole.