It depends on how they measure them. Often, US measurements are with all fluids and 1/2 tank of fuel.

The 1200s outside of US sometimes have no heater. The 1973 US models have heavier bumpers and side-door safety beams.

4-Dr-Sedan is lighter then Coupe
I doubt that ... but the Australian Coupe has carpeting, heater, clock, tacho, etc. While the basic 4-dr might be lacking all that unecessary equipment.