Install-SPSolution command can accept an optional
Synchronize parameter. MSDN says that it "synchronizes all solutions or the specified solution in the local farm". But what does this mean? What exactly does the parameter do? When should it be used?
A bit of detail.
Performs a synchronization of the Windows SharePoint Services Solution Package (WSP) solutions stored in the configuration database with the files stored on disk. The .wsp files will be synchronized in the order in which they were submitted to the server.
This is same as Syncsolution in SP 2007.
So bottom line, Synchronization is done within two things
Changes in File System WITH Changes in Content DB