Hmm... both use the gnome desktop so the "feel" should be much the same. You can theme all the parts separately and move things around on the bars to suit your needs, so not too sure what you mean?
As to learning the only way to do so is to try it - arch is a binary distro so anything you do install will work. I'd suggest trying out different desktops first though, at least kde and enlightenment 17, maybe xfce as well... once you know which you prefer you can start to consider what's going on behind the scenes.
Are you hoping to become a programmer or write shell scripts or just use the computer online without fear from viruses? Most linux security updates relate to local exploits which means someone sat at your computer. If they're that close it's probably too late anyway