I guess some analysis comparing the leaked Alpha to the final in terms of page count:
Chapter 1: Step-by-Step Characters
Alpha: 7 pages
Final: 6 pages
Likely due to just text size and formatting
Chapter 2: Races
Alpha: 8 pages
Final: 25 pages
The large difference here is likely due to a lot of art of all the races being added in.
Chapter 3: Classes
Alpha: 82 pages
Final: 76 pages
Between art being added and formatting, we can be fairly sure that no major changes to the classes occurred. At the very least there isn't a bunch of class options added that weren't in the Alpha.
Chapter 4: Personality and Background
Alpha: Missing from the leaked Alpha
Final: 21 pages
It should be noted that if the formatting stays the same that means that each background takes a page. That means there are 17 of them.