The arms are the same. (they have a few different "editions" of them that supposedly have different charicteristics in the laminations but in talking to Orion, only the absolute top drivers would even feel the slightest difference in the performance of the motor. ) They just have no phenolic (sp?) washer and they have o-rings that they use as the last shim against the bearings.
These motors kick some serious butt too. I got a couple for offroad and they are great. After a 5 minute race in mod buggy I still have like 250 seconds left of runtime at 30 amps and the motor is barley warm and the car is sick fast.