While their specifications show an 8 pixel difference, I should realize that 8 pixels are around 0,7-0,9 mm depending on whether it is vertical or horizontal.
This is not a difference human eye can notice by putting devices side by side. We simple are not capable of making that measurement without assistance.
But the thing about eInk is that it is weird, you cannot compore it to computer screen, pixels are not aligned. Kindle is below.
This is a Cybook:
They are weird, as you can see. Incidentally, this is also why you should not hint you typefaces as if you are hinting for computer screen. And why most typefaces render weirdly.