This information comes from a private account on “X” that has an accurate track record when it comes to revealing Apple’s future plans. The version of iOS 18 that is being shipped right now is known as “VendorUI” and its access to it is reportedly strictly controlled. Apple sends out a ”VendorUI” version of the upcoming iOS build every year to factories for quality control.
The version of iOS 18 being disseminated now is shipped to factories for quality control testing
The reason why access to this version of iOS is so heavily guarded is because it can include references to new features, new settings, and any branding changes. The “VendorUI” version of iOS ships with some apps missing and only includes those apps needed for tests.
Each build of iOS has different versions with the Release version the one that consumers receive each September. The InternalUI version is created for Apple’s software engineers with unreleased and unannounced features. This version usually features a pre-production variant of the iOS UI. VendorUI is the version being released now and it can contain some pre-production UI elements although it is designed for quality control testing in factories.
As you might assume, NonUI does not come with the standard iOS UI and is designed for hardware engineers and calibration machines. Lastly, LLDiags carries no UI at all except for a small diagnostics menu and this build is used for low-level diagnostics.