Servicing
Package Manager replaces the previous Package Installer (Update.exe) and Update Installer (Hotfix.exe). It is part of the Windows Vista servicing stack. Updates for Windows Vista are delivered as files and resources only. Package Manager, the Control Panel item to turn on/off Windows features, and Windows Update all use the Windows Vista servicing stack. Package Manager can also be used to install updates to an offline Windows image, including updates, boot-critical device drivers, and language packs.
Read more about this topic: Management Features New To Windows Vista