The PDF version is a color extract of the book interior used to print the hardcover/softcover versions.
From the introduction:
This may surprise you if you’re holding a bound volume, but all the content contained within was either underwritten by the fans of the game REIGN, or was put up gratis by myself in order to promote and support it. […]
As well as I can achieve it, the contents include every word and image I’ve put up as a supplement, and most of the REIGN wiki. […]
So that’s what you’ve got: The first year of REIGN, in one gluttonous lump. Let’s hope we have as much fun in year two.