Peckish just contacted me about your question. I've used it on both, and now exclusively on my Mac. Absolutely no difference within the program between the two platforms. They both work exactly the same.

I have it on my Mac and PC. Both platforms are the same. You're only allowed to have the program, no matter the platform, only on 2 computers. You could have it on 2 Macs or 2 PCs or like I do but only on 2 machines.