Core differences:
Vehicle spawners are replaced with shops and the old car shops are removed
3 shops for different types of vehicles: Land vehicles, Aircraft and Boats
Cheaper prices
Vehicle panel is removed
Vehicle position is saved and vehicles cannot be teleported
Vehicle health is saved
/veh command to control various vehicle functions
Vehicle can be stored in a shop (to prevent someone from destroying it) and later be spawned in any shop
Armed vehicles (Rhino, Hunter, Hydra, Rustler, Sea Sparrow, Predator) for coins
Free vehicles that spawn randomly all over San Andreas
Vehicle is lost when it blows up
Modification shop is removed but you can select the vehicle's color when buying it (free of charge)
Nitrous can be included for extra cost when buying the vehicle
Vehicles cannot be sold

Everyone would be fully refunded for their current vehicles.