WSUS difference between Windows 10 and Windows 10 GDR-DU Products

GDR-DU mean General Distribution Release (Dynamic Update)

Sadly from TechNet no resource seem wrote for that. From the information I have it's file kept for upgrading from a build to another, to prevent a fresh system re-install (like build 1511 to 1607). (not for normal updating).

A description for GDR-DU from a Microsoft source there, official (but on an archived mailing list). (https://marc.info/?l=patchmanagement&m=147085158401556&w=2)

GDRDU just means that when you install Windows 10 1607, it will automatically download and inject the update as part of the upgrade process, as long as dynamic update is enabled (which is the default). It's a mechanism to get fixes in place without refreshing the entire OS image.

See there for a quick info, not official, but still point to the same answer than the Microsoft's source: http://www.urtech.ca/2016/12/solved-what-do-the-windows-10-product-names-mean-in-wsus/

Windows 10 GDR-DU: GDR = General Distribution Release, DU=Dynamic Update. These updates are only used by the current GDR build of Windows 10 when it is trying to perform a Dynamic Update (see item 5 above).

Item 5: Windows 10 Dynamic Update: This includes only updates to the setup process that occurs when one build of Windows 10 is trying to update to a new build of Windows 10 (i.e. 1511 to 1607).

A more generic description for GDR-DU.

By default, all components on Windows systems start on the GDR branch following each major release. When you install updates from Windows Update for a GDR component, it gets upgraded with the GDR version.

When you install a specific Hotfix, the files and components in the Hotfix package are migrated to the LDR branch. At this point, that particular component is marked as a LDR component. If you install a newer Update over this component, the Windows servicing technology will automatically install the appropriate latest version from the LDR branch for you. This is possible because each Update package ships with both the GDR and LDR versions of the component.

Once a component is marked as a LDR component, the only way to move back to the GDR branch is to uninstall all Hotfixes for that component, or move to the next available service pack.

Quoted text from https://blogs.msdn.microsoft.com/ntdebugging/2008/10/21/windows-hotfixes-and-updates-how-do-they-work/

The question after is, why you can select GDR-DU alone without the Dynamic Update too.