quite a lot. Snow goggles are much more cylindrical, the ventilation is different to work with different helmet styles, the strap in the MTB goggles are set farther into the lens instead of next to it (So that the goggle can recess more into the full face helmet and actually touch your face) They have tear off tabs if need-be, they are far more inexpensive for the cheap pinkbike users like most of us, and they also come with a clear lens as the second instead of a lowlight lens.