The real difference between Diet Coke and Coke Zero

Both Diet Coke and Coke Zero are marketed towards drinkers of soft drinks who are concerned with keeping an eye on their weight. Neither one contains any sugar or calories. However, the two sodas (might) taste different because each beverage uses a different formula, with differing types of flavorings and sugar substitutes (via Coca-Cola Company).

While a look at the labels of the beverages is sometimes less than helpful due to the vagueness of terms like "natural flavors," a few differences can be gleaned. For both sodas, the first couple of ingredients are the same — carbonated water and caramel color (via Huff Post). In Diet Coke, the third ingredient is aspartame and the fourth is phosphoric acid, whereas in Coke Zero, they are flipped. Coke Zero contains acesulfame potassium, a sweetener, and potassium citrate, a common soft drink additive, while Diet Coke doesn't contain either of those ingredients, and appears to rely on aspartame for sweetening.

Coke Zero takes the lead

Though the ingredients differ slightly, the beverages have the exact same nutritional values. Zeros across the board except for 40 milligrams of sodium, which they share. Diet Coke was introduced to the market in 1982, almost a century after the original Coca-Cola was invented in 1886 (via Coca-Cola Company). Coke Zero, on the other hand — it was rebranded as Coke Zero Sugar in 2017 — was introduced in 2005 (via Coca-Cola Company).

While fans tend to feel very strongly about one formula or the other, just over half of a focus group was able to taste the difference between Coke Zero and Diet Coke, suggesting that they might not be all that different after all. Meanwhile, Coke Zero has done quite well since its introduction, and Diet Coke has suffered as a result. Consider that in 2016, Coke Zero sales increased by 3.5 percent, while sales of Diet Coke dropped almost 2 percent. Even Coca-Cola executives said that the success of Coke Zero was "cannibalizing" the market for Diet Coke, and even Coca-Cola (via Business Insider).