Looking at the home screens, the primary difference you'll find is that in iOS 26 the background of the dock and the search option that sits in between the dock and the home screen icons are more transparent and have a sheen to the edges, whereas in iOS 18, these are slightly darker.

With the introduction of OS version 26, Apple streamlined the user interface across iOS, iPadOS, macOS, watchOS, tvOS, and visionOS. Liquid Glass is now the company’s universal design language, borrowing cues from the Vision Pro’s operating system and preparing for a future dominated by mixed-reality gadgets.

Apple 's Liquid Glass design is, by far, the most polarizing feature in iOS 26.