Four gigs of Ram - is a bit of a pinch. I think you may see some slowness but for casual browsing, photo viewing or editing, watching a video or two... Core should be able to do fine.
I believe XFCE (lite) may be a little lighter on the CPU and other resources.
What you might do is try both in one go, if you don't mind configuring your Zorin OS install a bit. You can install Core and test it out. Then open a terminal and install the XFCE4 desktop:
sudo apt install xfce4
This will likely lead to you installing and setting up LightDM instead of GDM3 - Say yes at the prompts - when complete, log out and log in - click the DESKTOP chooser icon on the upper Right side of the toolbar (The icon itself will be the leftmost icon in that area) and choose XFCE desktop.
Then test that.
This option will allow you to explore how both D.E.'s function within just One Install. If you prefer one D.E. over the other, you can just stay logged into that one. Or, remove XFCE4 if it doesn't make the cut.