Edit Just to give some examples:
Here's white markings, symbol + regulatory markings, various colors (black missing), and two surface finishes - matte and spun metal (I think was limited to the blue and red ones)
Here's the difference between non-finished and matte finish on black ones:
The non-finished ones were the early ones, no regulatory markings. The original promo image also shows the gold-ish printing on the silver unit:
Here's a good picture showing the differences in red hues between editions:
