Nope - they all vary in size. The original plan for World Showcase was to locate it next to the T&TC, in 2 curving buildings around a plaza. Each country would have exactly the same ammount of frontage onto the plaza, but could build backwards as far as they needed.
Once America came down off its legs in todays World Showcase plaza it was moved to its current central location (originaly a lake and fountain) since it is the host nation, and so no others could be perceived as having preferential treatment. Strangely, each country that was added to the various masterplans in the late 70`s stayed in position (unlike the Futureworld pavilions)
Switzerland it seems was to go between Germany and Italy - at the time an expansion of Japan was planed, including the Ginzai (sp) district in the Meet the World building, and the Mt. Fuji rollercoaster, on the plot between Japan and Morocco. To balance the skyline with these 2 mountains, they were to be equidistant from America.
A phase 2 plan (as discussed elsewhere) had Germany and Italy adding water based rides, planned from the outset, so perhaps they are neighbours to share the pump and filtration systems?
China and Canada may be as far apart as possible to separate their common attraction technology
Morocco I can only guess was added where it is in `84 to fill in the gap between France and Japan.
The UK was to have a crystal palace stage show as part of a phase 2 (hence the village square to nowhere) - this required a large ammount of land behind it. Same for Italys gondola ride (Germanys river ride building was mostly constructed but never used, same as Japans `Meet the World` carousel theatre building.
Finally France was to have an exposition hall added as part of a phase 2 which needed extra room, and its current plot has plenty.
Either that, or someone played pin the tail on the donkey with a map of World Showcase :lol: