The recipe for Coca-Cola changes depending on the location of
the factory.
There are 2 ways in which Coca-Cola is sweetened, either by cane
sugar - or by high-fructose corn syrup, depending on which is
cheaper in the locality of the factory. Apparently the cane sugar
Coke tastes better.
In america "mexican coke" is quite popular because it uses cane
sugar as opposed to american which uses syrup.
If there is a difference; thats probably it ;)