This fall, the iPhone will undergo two massive transformations that will fragment it in ways previously thought impossible. First, Apple Intelligence will only run on iPhone 16 and iPhone 15 Pro models, which means your iOS 18 experience will differ depending on your hardware.
Second, the European Union (EU) is getting its own iPhone update that has nothing to do with hardware or Apple Intelligence. On that note, Apple Intelligence isn't even coming to supported devices in Europe when the US and the rest of the world will get it.