In hands on video they were comparing them and said with the light at 0% the background was much whiter than the NST and Kindle Touch. You can find those on YouTube if you go searching.
I am excited because I have seen how much Amazon improved the K4's background and contrast compared to last year's model so I have high expectations for the PW.
I can not began to describe how gorgeous the K4B is. Every time I turn it on I sigh happily because it really is a huge improvement. The off white background and black text are something I always wanted on my eReaders. The K3 came close. The K4S was a step back but this year's models seem to be near perfect. I can't wait to get a PW it will be my birthday present.
