Elementary OS is a desktop distribution based on Ubuntu Desktop, and like many or most distribution based on Ubuntu Desktop, does not use the parent distribution’s Unity desktop. It also does not use the GNOME Shell either.

Rather, it uses a custom desktop interface called Pantheon, which like the Depth Desktop Environment of Linux Deepin, is built atop GNOME 3 technologies.

Pantheon is the latest in a series of desktop environments built atop GNOME 3 technologies that have arisen mostly because of dissatisfaction with Unity and the GNOME Shell and a desire from independent developers to do something better. Whether they are actually doing something better is questionable, but I’ll live that discussion for another time.