Kali Linux: from light to full distro

The sets of packages installed for the various flavours of Kali are defined in live-build-config. In this instance you need to look at the set of packages in Kali light and packages in Kali full: the latter adds kali-linux-full and kali-desktop-gnome.

So to get all the utilities installed in Kali full:

sudo apt-get install kali-linux-full

If you want to install the GNOME 3 desktop used by default in Kali full:

sudo apt-get install kali-desktop-gnome

If you want to uninstall the XFCE desktop used by default in Kali light:

sudo apt-get purge kali-desktop-xfce

You can use the full set of utilities from the XFCE desktop, so you may want to try out the various possibilities before uninstalling anything.