the wing loading is literally how many Ounces (or pounds) each sqaure inch (or suqare foor) of the wing must lift to make the airplane fly. (a 100 Sq in wing on a 10 oz airplane... 100 Sq inches must lift 10 ounces... 1 Sq Inch must lift .1 ounce.... .1 Oz per Sq In.)
so if you've got 2 different sizes of the same airplane, say a .40 and a .90,
if the .90 has twice the wing area and weighs twice as much as the .40 version, the wing loading on both airplanes will be the SAME,
but the bigger airplane is going to fly better because of reynolds effect. (bigger airplanes fly better than little ones do.)