Isn't Mac these days a UNIX-like OS on x86? What happens if you just move a Mac binary to a Linux machine (with all its dependencies) and try to run it?
I'm assuming it'll break, but what difference between the two OS's makes it break?
I'm assuming it'll break, but what difference between the two OS's makes it break?
Not exactly. Mac OS does include a BSD subsystem and behaves more like a Unix than it behaves like Windows. But it is still significantly it's own thing.
The Mac kernel is XNU. Nearly all Mac apps use Cocoa. The Mac filesystem is HFS+. Hardware is managed through IOKit. The list goes on but basically every major system service is written for Mac OS and does not have any direct compatibility with other OSes.
More to the point, there's the lack of Mac-specific frameworks (e.g. Cocoa) on which most Mac applications rely.