WizTree also understands things like OneDrive and Dropbox, and know that files "stored in the cloud" aren't taking up any disc space -- WinDirStat thinks my drive is 140% full.
Wiztree and WinDirStat will both double count hard links. I have a 12TB hard drive holding "17TB" because of sparse files and hard links. Windows file manager properties agree with Wiztree and WinDirStat as far as space used. I think the file manager looks for free space and calculates that separately, while Wiztree and WinDirStat are just adding up used space.
