Which desktop environment does Zorin OS use and how to get for Ubuntu?

Zorin OS use Gnome 3 Desktop Environment with customized themes. To install Gnome 3 use the following command:

sudo apt-get update && sudo apt-get install gnome-shell ubuntu-gnome-desktop

Then you need to get the themes from Zorin OS and apply to your Gnome installation. Since Zorin OS uses Ubuntu as base for it's packages it's simplier to install Zorin than to apply the themes to Ubuntu.

To install ZorinOS themes open Terminal (Press Ctrl+Alt+T) and type the following commands:

sudo add-apt-repository ppa:noobslab/themes
sudo apt-get update
sudo apt-get install zorinos-themes

To install ZorinOS icons open Terminal (Press Ctrl+Alt+T) type the following commands:

sudo add-apt-repository ppa:noobslab/icons2
sudo apt-get update
sudo apt-get install zorinos-icons