Jeremy White has agreed to answer a few questions and to explain how is software works :
” CrossOver is built using two core technologies – a customized version of Wine and a customized version of X11.
Wine is an implementation of the Windows API for Unix systems (note that Mac OS X is a Unix system). On Intel processor based Unix systems, it lets you load and run Windows executable files as though they were native to the Macintosh system.
The way I encourage people to think of it is as a ‘compatibility layer’. From a technical standpoint, it is very different than a virtual machine technology such as Parallels. Virtual Machine technologies let you emulate a PC, and then install + run Windows on that virtual system.
CrossOver, in contrast, does not install or require any Microsoft Windows. Instead, it simply determines what a given application requires from the Windows API, and implements those features using Mac OS tools.
Further, CrossOver runs the Windows applications directly; as the Windows programs are just Intel code, they run at full native speed. We can even provide connections for things
like access to graphics and sound that are difficult for virtualization products.
A very simplistic way to think of it is that if a Windows application is a car that wants to ride on
the rails, then Parallels is like a boxcar that scoops up and holds a chunk of road along with your car. CrossOver is like a set of adaptors that lets your wheels go directly on the rails. “