Ishazi
I'll just ask the DM
The biggest difference between 3.5 and Pathfinder is, how the two deal with combat "tricks"[trip, bull rush, disarm, sunder]. Beyond that much of the classes are just enhanced with new features and better hd[example; wizards get a d6 per level, instead of a d4. Rogues and Barbarians get new abilites called Rogue tricks and Rage powers, respectfully. So, on and so forth].
Two really good websites are
Pathfinder Roleplaying Game Reference Document Everything that is Open Licensed, and Paizo make, is here
And
D20 PFSRD (this also includes 3rd party add-ons to the system, some are very well balanced others... not so much. For this, I will only allow the Psionic's option in this one, besides base.)