If you pour a Mountain Dew into a glass and a Mountain Dew Throwback into a glass the color is slightly different (very slight). Also, the throwback has smaller bubbles for a smoother mouth feel than regular Mountain Dew.
In terms of taste, texture, mouth feel etc soda sweetened with cane/beet sugar tends to be more enjoyable in my opinion.
While I like the Coca-Cola that is bottle in Mexico, its actually in violation of agreements between Coke Bottlers. For instance coke bottled in New York isn't sold in Tennessee. Each bottler has 'territory'... the Mexican bottlers who sell to distributors have no way of knowing were the coke ends up so its not their 'fault' but puts them in a bad spot, and has caused a lot of controversy.
Wal-mart had to stop carrying the Mexican botled Coke in order to avoid losing its contracts with local bottlers. A handful might still carry it, though I highly doubt it, as Coca-Cola= a ton of profit for Wal-Mart.
pepsico launched a product fairly recently 'pepsi natural' here in the US, and had 'pepsi raw' in the UK. Suprising to me the 'throwback' started in Mexico and was 'pepsi vintage' IIRC. There is a forum I joined just this week actually bevnet (google it, i can't remember the site) that has a ton of info on beverages.