The Crust has a lot of nice little flourishes. Just look at the head badge and biplane fork and sparkly paint. The Troll... doesn't.
Troll has braze-ons for V-brakes, Rohloff hub, and Surly trailer hitch. The fork has a lot more mounts. It's basically a big adapter for all the parts you can think of.
I bet the Crust is a lot lighter though I've got no basis for that.
Crust is a small brand of recent origin, doing small batches. Surly is a subsidiary of QBP and is available nationwide, they were some of the first to mass market fat bikes and then plus bikes.
Crust marketing: Try this bicycle I made, I really like it! Surly marketing: lots of cussing
__________________
Genesis 49:16-17