Is there a way to know what the Windows Disk Cleanup utility will delete?
Solution 1:
Generally, CCleaner doesn't check things like Windows Update temporary/cache files, and those files are usually very big. To clean up the Windows Update cache is not an easy task since I guess it requires complex dependency checking, knowledge about Windows Update state, etc. which is not something that a 3rd party tool can easily know.
It is normal for Disk Cleanup to be able to clean huge amount of file that CCleaner can't.