The Pavilion are consumer notebooks and the Probook are business notebooks.
Typically business notebooks are better built, and have more BIOS options than consumer notebooks.
The good thing about the consumer notebooks is they normally come standard with better graphics for gaming, etc. You normally have to pay extra for better graphics in the business notebooks.
If you want it to last for 3-4 years (with the extended warranty) then the Pavillion will offer you a better bang for buck than the Probook. If you are looking for a longer laptop life then Probook is the way to go.