Very often, products that are made in Canada and the United States will have different compositions in the two countries. "American" Smarties are a small round tablet-shaped sugar based confection. Canadian Smarties are closer to M&M's in appearance, having a chocolate base instead of a sugar base.
Also, sodapop (pop or soda, you decide, though it is usually called pop in Western New York.) in the United States is made with high fructose corn syrup due to high tarrif on sugar. In Canada, pop is made with sugar, which makes a cross-border shopping run that much more sweet.