Actually, Schweppes and Canada Dry are just brand names of the company that owns them - Coca Cola. In some places, both the Schweppes and the Canada Dry branding appear on the same ginger ale label. My guess is that, like so many other things, rather than sell the same product all over the world, they tweak the recipe to suit the taste of the local market. Personally, although I usually choose Canada Dry for nostalgic reasons, I don't think it's tasted the way I remember it from my childhood for ages - wherever in the world I'm drinking it.