what is the diff between towing cap & 5th wheel towing cap

Probably 19,840...a 5er puts the hitch weight in the bed over the rear axle, where a conventional trailer attaches to the frame at the back of the truck. The distance between the axle and the back of the truck acts as a lever arm on a conventional trailer so puts added stress on the suspension, where the 5er's pin weight is loading straight down.