Core is replacing lite because it's supposedly as efficient and conservative on system resources?
But what are these 2 like in the real world on an old computer with just 2GB RAM? And which would you recommend and why?
The main difference between Core and Lite is the underlying desktop technology used — Gnome and XFCE, respectively.
I've only used Gnome on computers with at least 8 GB so I can't really compare it accurately with XFCE, which I've managed to run it in computers with as little as 1.5 GB of RAM. However, I think this comparison almost speaks for itself: XFCE is very suitable for devices with limited resources.
Zorin OS Core in particular implements quite a few extra animations and visual effects. If you disable those (in Zorin Appearance → Effects, I think) you will get better performance.
That said, I see no reason to risk it, and I would recommend going with Zorin OS Lite which is much more likely to work on your device. Consider that it is one thing to run the desktop itself, but then you need to add whatever applications you're going to be using on top of it.
With 2 GB, lite (XFCE) is the way to go.
Lite makes the most sense for systems with 2GB of RAM.
With just 2 Gig's ... Lite would be the better Try here I think. But there is a Point: Do You have an integrated Graphics? If yes, there would be the Point, that this igPU takes something from the RAM for the Graphics which means You would have even less.
I heart a While ago from miniOS. It is intended to use on USB Sticks but You can install it, too. It uses xfce and needs not much RAM. Maybe this is a better Choice for You.
I mean: Beneath the System itself, the Programs what You use, need RAM, too.
With 2 Gb of RAM i would recommend Lite.
Even if the official hardware requirements says 2 Gb is enough for Core, it will probably not work correctly (4 Gb should probably be the requirements for Core)
A reminder:
2 gigabytes is the minimum to install Zorin OS; not the minimum for Performance.
And this is why.