1. Backgrounds provide a basic level in skills and a base amount of Wealth.
2. Occupations can be changed several times over the course of your career and provide Wealth, skill access, feat access, improved feats and perks.
3. Hobbies provide a basic level in a single skill.
4. Wealth still exists but is not used to roll wealth checks.
5. Basic, Advanced and Prestige Classes are gone replaced with six archetypes.
6. Skills have been streamlined considerably and can be extensively modified by perks. Several skills have been changed or merged. Some new skills have been added.
7. Opposed skill checks are gone, replaced with targeted checks.
8. Many skill checks (such as for crafting) have been completely eliminated. The skills themselves have been folded into new skills, while the skill checks are no longer made. Your total ranks in the skill determines what you can and cannot build.
9. Many feats have been eliminated, their place taken by new skills and perks.
10. Critical hits are gone. In their place, a number of abilities grant a character bonus damage based on his attack roll.