The Copper Spur is about a foot and a half (about half a meter?) wider at the head end of the tent, which gives you significantly more room to move around and store gear. Also, both tents have an entry vestibule and a small rear vestibule (where you guy out the back of the tent.) However, the Copper Spur has a zipper that actually lets you access the rear vestibule from inside the tent; the Hubba does not.

By the way, Franco's post reminded me of another tent that might work well for you: the Tarptent Rainbow. It's a single-wall equivalent of the Hubba, but nearly twice as wide and only weighs 2 pounds. I've had one, and it's incredibly roomy, well-made, and about a foot longer than the Copper Spur. I never developed the "warm fuzzies" for it, but it has loads of fans. It might be something to look at while you're checking out the Scarp.