Deduplicating (aka optimizing) exposes four different types of ‘jobs’ that can be done.
GarbageCollection – Checks the ‘Chunk Store’ for chunks that are no longer in use and removes them.
Optimization – Optimizes the volume by removing redundant ‘chunks’.
Scrubbing – Used for checking integrity and validate the checksum data. Think of it as a CHKDSK for Dedup.
UnOptimization – This job will probably not be used that often. It puts NTFS back into its legacy or unoptimized state. Normally you would only want to do this if you were moving the volume to a downlevel server.
NOTE: Deduplication at the file system level was first introduced in Windows Server 2012.