Fusion offers the option to reclaim disk space at the bottom of the VM Library window and in Settings>General>Clean Up Virtual Machine, and the process is both quick and often productive on Windows VM's.
Disk Shrink is run as a VMwareToolboxCmd within a running Windows (or other) VM, can take quite a while and doesn't seem to do much on a Windows VM (it's great on Linux or Mac OS X).
For Windows, what is each VM size reduction process actually doing and is there any circumstance when Disk Shrink is beneficial? And does either do any of what Windows' Disk Cleanup does?