Yes, it makes my head spin too. The SR5 can tow 9,800. Mine can tow 9,970. Just a much heavier truck empty that's all and it might help with controlling the trailer when swerving to avoid a chicken crossing the road.
"Your curb weight represents your vehicle’s weight with all of the standard equipment and amenities, it doesn’t include any cargo or passengers. Gross vehicle weight, on the other hand, does include the additional weight of your passengers and cargo."