If you've ever tried Coke that was made in Mexico, you may or may not have tasted a difference. While enough people find the Coke from south of the border appealing to have Costco stock it, there are not very many differences, actually. On the surface, there is really only one major difference between Mexican Coke and Coke made in the United States (via Smithsonian).
That primary difference comes down to sweeteners. Mexican Coke is made with cane sugar while American Coke is made with high fructose corn syrup. Some people believe that cane sugar tastes more real and less like chemicals. Others think cane sugar is actually healthier, but gram for gram, both kinds of sugar pack the same number of calories and can cause the same problems.
Another difference that could affect the difference in taste between the two kinds of Coke is the materials in which they are packaged. Plastic and metal cans that American Coke comes in can affect its taste, and Mexican Coke comes in glass bottles, which might help it to maintain a better flavor. Some even claim Mexican Coke is more effervescent (via Creager).
The complicated history of Mexican Coke
The Mexican government has attempted to pass a tax on high fructose corn syrup twice, one in 1997 and again in 2002. In both cases, the World Trade Organization weighed in favor of the United States. In both instances, the Mexican government was attempting to make cane sugar more profitable for sugar cane farmers, who some claim were being forced out of business while trying to compete with U.S. prices.
Ultimately, Mexican Coke has become something of a symbol of ethical consumption that supports smaller businesses. It also tends to represent anti-globalization. Ironically, this is still a Coke product that is part of a massive, world-wide company. While Coke seems to be something of an ever-evolving political statement, it sounds as though Mexican Coke will continue to be the Coke of choice for hipsters, in-the-know restaurants, and those who just like that iteration of the bubbly soda best.