What I can see on B&H is they are both for autofocus use of EF Glass on X mount but there is a $100 difference. I couldn’t find anything using search on the difference.
TIA
Mike
Pro II - Aperture ring, chrome plated brass mounts on both ends
Pro III - Aperture ring, chrome plated brass mounts on both ends, weather sealing
EF-FX II (not pro) - no aperture ring, lens side mount is chrome plated brass, camera side mount is anodized aluminum
AF capabilities should be identical for all three.