MU will be the new Windows Update service, and will provide a single service for users to get patches for a number of Microsoft products, not just Windows. WSUS, on the other hand, is a progression from the existing Software Update Services (SUS) tool, a patch management tool for business users.
Like MU, WSUS also offers patches for Windows operating systems as well as Office XP, Office 2003, SQL Server, MSDE (Microsoft Desktop Engine), Exchange 2000 Server and Exchange Server 2003 products.
The WSUS client will run on versions of Windows 2000 with Service Pack 3 and beyond and on all Windows XP releases. The WSUS server requires Windows 2000 Service Pack 4 and later or Windows Server 2003, Microsoft said.
WSUS is currently available in release candidate version, the final before release, said Jason Leznek, a product manager at Microsoft. The product has undergone two name changes. It was originally called SUS 2.0 and then renamed Windows Update Services. It got the Windows Server Update Services name earlier this year.