Coke is actually very different from country to country and less so from state to state. This is because Coke uses local bottle companies and they might be using different water. The coke you buy at your local store is probably bottled somewhere close to keep shipping costs down.

If you're a fan of Dr.Pepper, you'll notice they have 2 different bottles based on where you buy. That's because in some regions, Dr.Pepper uses Pepsi for bottling and in others it uses Coke bottlers.