Something that I forgot but need to add to this:
Installing XFCE4 on Zorin Core can be done as above, but a quick note on something that is missing from that that any users with a number in their login password may just want: Enabling numlock on login
sudo apt install numlockx
sudo nano /etc/lightdm/lightdm.conf
Add this line: greeter-setup-script=/usr/bin/numlockx on and save and exit.