You guys made me check the numbers - a Land Rover Defender 110 has a GVW of 7055 lbs. The JK Unlimited GVW is 5700 lbs, a difference of 1355 lbs.
I realized I should have posted the curb weight as well as the GVW for both so we could see the cargo capacity.
JKU: Curb weight 3,879 to 4,921 lbs. (seems to average about 4500), GVW 5700, load capacity (average) 1200 lbs.
Defender: Curb weight about 4815-5165 lbs. (average about 5000), GVW 7055, load capacity (average) = 2055 lbs.
So it depends a lot on how your JKU is configured from the factory and how a Defender is configured, but average numbers suggest that an average Defender will have about 800 lbs. more load capacity than an average JKU.
Not 100% sure about all of those numbers, I found a number of sources listing different weights, but I think the average difference is probably a reasonable estimate.