The iOS 18 beta version differs slightly from the general release. Beta testers are given a release that has recently exited its alpha phase, so problems and bugs are expected to arise. The purpose of the beta phase is to gather user feedback to repair these bugs and address any user interface issues before the software is massively distributed.
Beta versions can also be incomplete and not the final product, especially in the case of iOS 18, which didn’t include Apple Intelligence features in the initial beta release. This means the iOS 18 beta version is more prone to bugs, glitches, and instability.
Also: Is iOS 18 tanking your iPhone battery? Here’s why, and what you can do
The general release will have ironed out most of these bugs and problems using the user feedback gathered during the beta phase, delivering more complete software that isn’t as prone to bugs, though they still happen, as we saw with the bugs in the iPhone Messages app.
One example of this process is when Apple released the iOS 17 beta version in 2023. The early beta version featured the “End” button during a call that had moved from the center to the right, which was a big change for iPhone users. Disapproving feedback from beta testers resulted in Apple moving the “End” button back to the center of the screen, where users had been accustomed to.
Source : https://www.zdnet.com/article/every-iphone-model-compatible-with-apples-ios-18-and-which-ones-arent/#ftag=RSSbaffb68
