Forum Discussion
Windows Update: Deadline vs. Deferral
When you defer feature updates, new Windows features won’t be offered, downloaded, or installed for a period of time that is greater than the deferral period set. Deferring feature updates doesn’t affect security updates, but it does prevent you from getting the latest Windows features as soon as they're available.
https://support.microsoft.com/en-us/help/4026834/windows-10-defer-feature-updates
About Deadline:
Although you can decide when automatic updates and restarts should occur, you can only set deadlines for up to 30 days for a feature and quality updates, and you can only postpone a restart for up to 7 days. Also, using this policy, users won't be allowed to reschedule a restart.
Deadline allows specifying the number of days that a user has before quality and feature updates are installed on their device automatically. Also, there is an option to set a grace period after which the operating system restarts automatically.
this article explains about Deadline policy:
https://winaero.com/blog/set-deadlines-automatic-updates-restarts-windows-10/
Enforcing compliance deadlines for updates
https://docs.microsoft.com/en-us/windows/deployment/update/wufb-compliancedeadlines