Diet Coke
Diet Coke does not use a modified form of the Coca-Cola recipe, but instead an entirely different formula. The controversial New Coke, introduced in 1985, used a version of the Diet Coke recipe that contained high fructose corn syrup and had a slightly different balance of ingredients. In 2004, Coca-Cola introduced Coca-Cola C2, which it claims tastes much closer to Coca-Cola but contains half the carbohydrates. In 2005, the company introduced Coca-Cola Zero (replaced by "Coca-Cola Zero Sugar" in 2017), a sugar-free variation of regular Coca-Cola.
Diet Coke
According to the Coca-Cola Company, "[t]he sweetener blend used for Diet Coke/Coca-Cola Light is formulated for each country based on consumer preference." Some countries began using the term "Coca-Cola Light" as early as the 1990s, with others adopting the name later on, while others continue the use of "Diet Coke".