This seems to suggest that it is easier to tell the difference between Coke and Pepsi than it is to tell the difference between regular and diet. I can tell the difference between all of them, but the first is a lot harder and I think that experience is pretty common. Most diet drinks use aspartame as a sugar substitute and aspartame leaves a very distinctive aftertaste in my mouth.
This seems to suggest that it is easier to tell the difference between Coke and Pepsi than it is to tell the difference between regular and diet. I can tell the difference between all of them, but the first is a lot harder and I think that experience is pretty common. Most diet drinks use aspartame as a sugar substitute and aspartame leaves a very distinctive aftertaste in my mouth.