For those of you who think you can't tell the difference, or it's very "subtle", are you properly inhaling the drink? Make sure you inhale the fumes slowly and with agitation of the drink in your mouth, and exhale slowly while the drink covers your tongue. I also suggest doing this with chilled bottle or can; fountain beverages add a lot of randomness to the mix.

Human variance being what it is, I'm sure the result will still be indistinguishable to some people, but I also think there's a lot of people who will suddenly be able to tell the difference quite strongly after this exercise. They're certainly in the same "genre" of drink, but quite substantially different. After this exercise you may also understand why Coke is strongly favored for mixed drink applications. (I mean, to the extent that either is favored. Still, "Rum and Coke" is a thing; "Rum and Pepsi", well, it may get you what you ask for, but you may get a bit of a "look" from the bartender.)

(I was raised fairly typically midwest American, and the injunction to keep your mouth closed while eating was rigorously enforced. I have often wondered if the resulting non-inhalation of the food's volatiles has contributed to the generally poor quality of American cuisine at the time, and its slow progress since then. I've also wondered if "don't inhale your food!", which figuratively means not to eat it too rapidly, also has the literal meaning resonate in our brains and prevent us from doing the good and proper kind of inhalation.)