I have all three models of the Paperwhite and I've helped a lot of my neighbors get their own Paperwhites, again, all three models over the years. There's a lot of variation in individual devices as HarryT has said. In fact some of the Paperwhites of the same generation vary more than the difference in my Paperwhite 3 and my Voyage. Some even more than my Paperwhite 1 and my original Kobo Aura, and those are very different screens.
The differences I've seen are in color more than anything else, although there are sometimes differences in the evenness of the light. The colors vary a lot more widely than I would have expected.
Anyway I think before you can say with authority that one model is whiter than another you really have to compare a lot of devices. I don't think I've compared enough of them to say that and I've compared quite a few.
Barry
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