Here are some terms you'll see when shopping for a tow vehicle or RV:
GVWR - Gross Vehicle Weight Rating
This is the maximum total weight the vehicle and its contents or trailer and its contents is allowed to weigh according to the design specifications of the manufacturer. Don't go over the GVWR!
GCWR - Gross Combined Weight Rating
This is the maximum total combined weight that the vehicle and anything it is pulling is allowed to weigh according to the design specifications of the manufacturer. This rating can also be used as a gauge for what towing performance might be like. The closer you get to this rating, the worse towing performance may get, especially in windy or hilly conditions.
GAWR - Gross Axle Weight Rating
The maximum weight that can be carried by the axle, including the tire and wheel.
UVW - Unloaded Vehicle Weight
Sometimes referred to as "dry weight", this is what the vehcile or RV is supposed to weigh empty. It also usually (but not always) implies a "basic" or "standard" model...no optional equipment.
TW - Tongue Weight
This is how much weight is on the trailer tongue and is usually measured when the trailer is empty.
NCC - Net Carrying Capacity
This is how much additional (cargo) weight the vehicle or RV can carry. Be careful with this one though. The manufacturers use a simple formula...GVWR minus UVW...to come up with this one, so it doesn't include the weight of any optional equipment.