The biggest notable change in this build is the inclusion (finally) of OneDrive Files-On-Demand. This is essentially a reversion of OneDrive functionality to that which was available in Windows 8 and 8.1 - i.e. a file icon existed within your OneDrive heirachy *even if* you hadn't previously downloaded that file to your PC. Microsoft scrapped the functionality in Windows 10, citiing user confusion about which files / folders were and weren't local to a PC; but equally created a situation where whole folder structures appeared to be "missing" on a PC due to not being previously downloaded.
There's also a new GPU tab in Task Manager, allowing you to check what your graphics card is doing, work wise. It's maybe a bit of a geeky thing, but it's fun to have never-the-less.
Microsoft's full release notes are here: https://blogs.windows.com/windowsexperience/2017/06/21/announcing-windows-10-insider-preview-build-16226-pc/#CIf1X7VvIj5dHUlI.97