剛搜尋了一下TechNet，由
http://technet.microsoft.com/zh-tw/library/dd349799(WS.10).aspx
該文件中的這段敘述看來，
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Block Level Backup Engine Service
The Block Level Backup Engine Service (wbengine) performs block level backup and recovery of data. This service is used by the Backup and Restore Center in the Control Panel of Windows Vista and by the Windows Server Backup feature of Windows Server 2008. It allows for backups to occur at the hard disk level, instead of just file by file, in a process similar to disk imaging.

This service startup type is by default Manual.
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應該是僅限於系統映像的建立與還原功能上，才具備Block Level。