Actual Virtual Desktops provides a "virtual" space - as if you have several logical monitors instead of a single physical one. You can extend the real estate of the workspace and move a window from virtual desktop 1 to virtual desktop 2 etc. The actual number of virtual desktops is not limited!
As a multi-tasking OS, Windows allows you running multiple programs simultaneously. As a result, you have a few windows open at any time. But when working with lots of applications, your desktop can easily become overcrowded. Actual Virtual Desktops will help you resolve this problem - you can allocate and classify all of your windows by moving them to virtual desktops.