Updates
Updates to the Windows Desktop Update were part of IE 4.0 hotfixes and service packs. Later, shell security updates for Windows 95 and Windows NT 4.0 included both the update to the Windows Desktop Update version and the original version. Also sometimes the Windows Desktop Update version and the update to the original version were packaged separately.
The Windows Desktop Update also added the ability to create desk-bands like the quicklaunch bar. It also introduced new extensibility APIs for the Windows file manager, Explorer.exe (also a shell).
Read more about this topic: Windows Desktop Update