Apple starts disseminating a special build of iOS 18 on a controlled basis،
This information comes from a private account on “X” which has a clear history of revealing Apple's future plans. The version of iOS 18 which is currently shipping is known as “VendorUI” and access to it would be strictly controlled. Apple sends a “VendorUI” version of the next version of iOS to factories every year for quality control.

The currently released version of iOS 18 is being shipped to factories for quality control testing
The reason access to this version of iOS is so heavily monitored is because it may include references to new features, new settings, and any rebranding. The “VendorUI” version of iOS comes with some missing apps and only includes apps needed for testing.
Each version of iOS has different versions with the Release version that consumers receive every September. THE Internal user interface The version is created for Apple software engineers with new and unexpected features. This release usually features a pre-production variant of the iOS UI. ProviderUI is the currently released version and it may contain some pre-production UI elements, although it is designed for quality control testing in factories.
As you might assume, Non-UI does not come with the standard iOS user interface and is designed for hardware engineers and calibration machines. Finally, LLDiags has no user interface except for a small diagnostics menu and this version is used for low-level diagnostics.