I know this is an old-ish thread but I just covered the differences between counting calories, WW, and WWPP on my weight loss blog.
Basically it's this...
In the WW points system points were determined by calories, fiber and fat.
Considering 13 years of research since the points system was put into place, WW realized they needed to revamp their system. Research shows a lot, so WW made the PP system, which determines points based on carbs, fat, fiber and protein.
Most fruits and vegetables are also now of 0 point values, whereas they all (pretty much) had some sort of point value attached to them.