Mac vs Windows NL:
There are a few things about the Windows version that I wish the Mac version had, namely a few keyboard shortcuts that have to be selected with menu clicks on the Mac version.
The thing about the Mac version that I think is superior to the Windows version is the overall look and feel of it, especially the Sim. The colors seem more vibrant, the choice of fonts and such is a little classier looking, and riding the coasters on a 20" LCD monitor just looks fantastic. Granted, I could probably get a new video card for the PC, buy a new monitor, and tweak the color scale and get close... but why would I, when the Mac already does it?
In the editor, much is the same, although the buttons look better on OS X than they do in Windows (just as EVERY program's buttons look better on OS X, thanks to the Aqua interface). There is one quirk, however, in that there is no "Right View" button. There's a keyboard shortcut to see the coaster from the right side, but why there's no button for it is beyond me. No big loss, just a curiosity.
The differences between the two versions are minimal, at least what I've noticed of them. Perhaps others can point out more.
I think the MAIN difference is that I don't have to use a PC to play NL. Generally speaking, anything that I can do on the Mac is better than the same program on the PC, just because I'm not forced to use the PC.
...and I used to be a Mac hater!