What are you trying to lift?
Tractor manufactures usually do a pretty good job matching a loader to a machine. Whatever loader comes on the machine....you will have no issues lifting a bucket full of gravel, dirt, sand, etc.
Sure, some have stronger loaders. IT doesnt take a huge increase in cylinder size to get significantly more lift. Some manufactures do this, others dont. Everything comes in to play. The engineering of the loader mounting, front axle strength, machine weight, etc.
But some manufactures also put loaders on that in the real world, you are never gonna be able to make full use of them unless you chain the rear of the tractor to the ground.
So once you have reached usable lift capacity, and to keep the tractor stable, everything else is overkill.
But yes, some of the deere loaders are weaker than others. There are two loader options for the 3R series. The H160 is weaker and will barley lift over 7' high.The H165 however is more comparable to kioti, and will lift 8.5' high. Thats a huge difference.
Its just options to fill what people want.
What are your intended uses for the tractor and loader? Just general day to day moving dirt, stone, grading, etc. Or do you plan on digging stumps and moving pallets. Because being able to boast about having twice the lift capacity is pointless if you can only use half of that capacity because you cannot keep the rear end of the tractor down because you dont have 1000 pounds hanging off the 3PH