Gear VR has special sensors built into it, which interface with the phone, so you aren't using the phone's built-in accelerometer or gyroscope. Samsung has also put special effort into the rendering pipeline when in VR mode, so it has much higher priority than other processing. That's why it only works with the high-end Samsung phones, and not their lower offerings or other manufacturers.
I haven't gotten to try any myself, but I've read that the Gear VR has gotten the latency down below any noticeable level. So the main differences are more minor, like positional tracking and the FoV. And of course, that with an Oculus/Vive you're only limited by the power of your PC, which can be much better than a smartphone.
I haven't gotten to try any myself, but I've read that the Gear VR has gotten the latency down below any noticeable level. So the main differences are more minor, like positional tracking and the FoV. And of course, that with an Oculus/Vive you're only limited by the power of your PC, which can be much better than a smartphone.