Those are weight ratings, not actual weights.
GVWR is maximum permitted weight for the vehicle, whatever is installed or loaded into it.
GCWR is maximum permitted weight for the vehicle plus anything it is towing.
To find out the actual weight of any vehicle, you have to weigh it.
GCWR - GVWR = 6000 pounds, so if fully loaded you could theoretically tow that much. It is certainly enough for a light towed vehicle, providing you pay attention to Ford's limit of 1500 pounds for tows that do not have their own braking.
The RV manufacturer may have put a lower "maximum tow rating" on the RV, and has likely also put a maximum vertical load limit (sometimes called tongue weight) on the hitch as installed. These could be lower than the rating of the hitch itself, because the hitch is likely installed on an extension to the E-350 frame.
