GDP-PRO has all the features of the GDP-Light program, but has the following extra features:

Full transient burn-back (include ignitor mass flow, and engine filling and blow-down)  
Each propellant segment can be of a different propellant type
Burn options for each propellant segment (start burning of a segment x seconds after ignition, or start burning of a segment after another segment has burned a certain distance)
Nozzle erosion (tabulated input of erosion vs. time)
Checks for possible erosive burning of the rocket motor
No total propellant mass limitations (an export license is required)