(http://i.postimg.cc/J7HB1pnr/windows-key-keyboard.jpg)
There are many different types of updates for Windows 10, some of which are more important than others. To make things easier to manage, both for the company itself and for end-users, Microsoft is now integrating servicing stack updates (SSUs) into the latest cumulative updates (LCUs).
Cumulative updates should be familiar to most Windows 10 users, but SSUs are not something that everyone will be aware of. Nonetheless, the change Microsoft is introducing is an important one that should help to reduce update problems in the future.
SSUs are updates pushed out by Microsoft from time to time to fix problems that can prevent cumulative updates from installing -- and are therefore vital. Because of their importance, SSUs need to be installed before cumulative updates so that issues can be eliminated ahead of time.
By incorporating SSUs and LCUs into a single update, Microsoft is essentially streamlining the update process, reducing the need to check that updates are installed in the correct order.
The first update that works in this way is KB4601382 (http://support.microsoft.com/en-us/topic/february-24-2021-kb4601382-os-builds-19041-844-and-19042-844-preview-1a7ed2b4-017d-2644-a1e8-dd6bf14cba76), and in the release notes Microsoft says:
Starting with this release, Microsoft will combine the latest servicing stack update (SSU) for your operating system with the latest cumulative update (LCU). To utilize this improvement, install the most recent standalone SSU (KB4598481 (http://support.microsoft.com/en-us/topic/servicing-stack-update-for-windows-10-version-2004-and-20h2-january-12-2021-c8a86bf7-6d49-b7fe-4369-44b1429b33cf)) before installing this LCU. If you install this LCU before installing KB4598481, you might encounter error 0x800f0823 – CBS_E_NEW_SERVICING_STACK_REQUIRED. Close the error message and install the recommended SSU.
source (http://betanews.com/2021/02/25/microsoft-now-bundles-windows-10-servicing-stack-updates-with-cumulative-updates/)