It's not possible to specify exactly how much weight a suspension bridge can hold. This is because when the weight-bearing capacity of a suspension bridge is determined, a lot of factors come into consideration including bridge span, cable length, wind loads and active live loads.
The difference between a butte and a mesa is in their heights and size of the flat tops. A butte and a mesa are both geological landscape formations. Due to the forces of erosion, a mesa eventually gets reduced to a butte.