First things first – Han shot first!
Greedo was one of the second series of characters which mainly consisted of aliens and droids. The cardback image remained the same throughout the saga and would have remained the same had the character been released on a POTF cardback.
The photoart depicts Greedo in the cantina sitting opposite Han Solo. The image has been extensively airbrushed with the bottom portion of the picture being completely removed and the background around Greedo lightened to a light green colour with a mottled effect.
Greedo would have been carefully masked while the airbrushing was being carried out, which is how the character appears so sharp against the sprayed background.