Coca Cola is normally Kosher(did you know that. Most manufactured foods are) but Kosher for Passover is different. You could tell which bottles are Kosher for Passover because of the yellow caps. They are made with cane sugar instead of fructose. Those lucky Canadians have Coca Cola made with real sugar all year long. Although when Niel and I were in Canada their Coke didn't taste anything like the Kosher for Passover Coke.
One of my favorite sites, Not Martha conducted her own taste test. Go over and read her opinion on it as well.
Pic from All Over Albany.com