http://www.tomshardware.com/reviews/...er,3040-3.html
This came from the Tom's Hardware review of the K4 non-Touch. They seem to believe the K4 uses a cheaper batch... but, as far as I can tell, there's no real difference in grade, so much as individual QC on each screen. In the case of the Kindle Touch, either it was a bad screen n the demo, or else the lower height of the non-Touch bezel that let the light reflect better.