The preview build 22621.1635 for Windows 11 contains a number of new features, including a toggle that will set up your PC to prioritize getting the new non-security updates and enhancements.
The Release Preview also comes with a new setting to sync language setting to Regional format in the Microsoft account and adds application specific group rules to the firewall, and more fixes.
The new Windows 11 22621.1631 Release Preview build also adds a way to configure application group rules to firewall settings and also includes a number of bug fixes for various issues.
The new 22000.1879 build version for original Windows 11 Release Preview Insider Channel users is mostly a collection of bug fixes with a couple of minor new features included as well.