No Xamarin Studio on the mac vs on Windows. Logical I think because Windows has the real Visual Studio and Xamarin Studio Windows is based on GTK# (AFAIK, I think the mac UI is native Xam since last year) it is limited on the Windows side / feels quirky.
It feels much better on mac I must say, also tried it on Windows but just weird and slow.
I'm quite happy with it, but maybe I'm biased a bit because it sucked big time and they made big improvements to it last year. It's all relative ;-).