I prefer diet Pepsi, but for decades, bought whichever was cheapest that week. I had suffered from migraines for many years. Had all the tests etc etc etc. One day my son's girlfriend mentioned her mom could not drink diet Coke because it gave her a migraine.
The lightbulb exploded. In all the questionaires I had filled out I had simply listed diet soda, never distinguishing beween the two. Who knew????
I have no clue what the difference is between the two. I can drink Coke with no effects. But since eliminating diet coke, I have not had a single migraine.