Windows 10 Lean is a Windows 10 edition of "Diet", the operating system taking up less space on both the installation and after setup
Derived from the Windows 10 Pro edition, Lean releases some non-essential elements such as wallpaper and downloadable and post-installation system drivers using Windows Update. The result is a 2GB lower installation kit than the standard Windows 10 Pro version.
It is unclear whether Microsoft has created the new Windows 10 edition for use with limited devices in terms of available storage space, or just aims at more efficient use of available memory and reducing installation time
The Windows 10 Lean option will be available from the Windows 10 RedStone 5 update, expected to be officially launched in october March 2018 .