As it currently stands, the installation of the Windows 10 Anniversary Edition and the upcoming Creators Update is basically an in-place upgrade to a new version of Windows. These builds take a lot of time to download because they're so big and they also require a lot of time to install. This will change with UUP, this new update platform will enable Microsoft to roll out differential download packages that contain only the changes that have been made since the last time you updated your device.
By no longer having to roll out a full build to everyone, Microsoft estimates the download size can decrease by about 35 percent when going from one major update of Windows to the next.
One of the biggest community and customer benefits of UUP is the reduction you’ll see in download size on PCs. We have converged technologies in our build and publishing systems to enable differential downloads for all devices built on the Mobile and PC OS. A differential download package contains only the changes that have been made since the last time you updated your device, rather than a full build. As we rollout UUP, this will eventually be impactful for PCs where users can expect their download size to decrease by approximately 35% when going from one major update of Windows to another. We’re working on this now with the goal of supporting this for feature updates after the Windows 10 Creators Update; Insiders will see this sooner.The new Windows 10 Mobile builds for Windows Insiders received UUP support yesterday. The first Windows Insider version for the regular Windows 10 platform is expected later this year.
We have also revamped how devices check for updates, making them more efficient. As we move to UUP, we are reducing the update data sent to client devices as well as the amount of processing we are doing on devices, this especially important for devices built on the Mobile OS. Using UUP, when your device checks for updates, the Windows Update service will evaluate which updates are needed by a given device. The Windows Update service then returns these updates to the device for download and install. Because more processing is being done by the service, this will lead to faster checks for update operations. It’s important to note that with UUP, nothing will look or behave differently on the surface, UUP is all underlying platform and service optimization that happens behind the scenes.