All rersearch done and all info in house
will see if I have the time to do a review on this, but you have part of the answer in there!
Cases and back cases are identical, metal bezel specific to US version, the 2 acrylic bezels are similar, one is missing some paint in the dots, plexis are different between 6921-1 and 6921-2.
the 6921-2 has a generic service crown...
there are more differences!...more to come maybe