The coated glass is "index matched" on the VXIII, but not on the VariXIII. Whatever that means.
The coatings on the VX3 are entirely different. They are the blue light biased Diamond Coat 2 coatings. Many times harder than other coatings. The design of the scope has also improved ability to capture stray light.
The adjustments have an improved dual spring design to achieve more precise tracking. They are improved versions of what Leupold has used for years on it's Benchrest and tactical models.
These improved adjustments offer no improvement on how well their scopes hold zero according to my information. E
