Microsoft indicates that it is highly probable that multiple versions of Service Pack 1 will be offered for Windows Embedded Standard 7. Matthew Tundo, a software development engineer on the Windows Embedded team, explains that although the several different versions of each service pack will bring to the table the same updates, they will differ in the manner in which the upgrades will be deployed. Tundo cited Microsoft’s need to adapt the upgrades to a multitude of scenarios in order to deliver the best experience possible, and that the company will provide "Full" and "Small" service packs.
Full read here: Several SP1 Releases for Windows Embedded Standard 7 - Microsoft is offering the first details - Softpedia