I hope that I answered your question fully. There are versions of Linux that run on both ARM chips and Intel chips. It can look like a Mac, it can become a CLI interface, and can do a myriad of other things. Lastly, unlike Windows and Mac OSX, Linux is easily customizable. Wheezy is based off of Debian, but there are also other forms such as Ubuntu, and Arch Linux. 'Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution.' - Wikipedia This means that anyone can modify Linux as the kernel is available freely (both in free food and free speech.) Unlike OSX, there are many different 'forks' or 'flavors' of Linux.

Lastly, I seriously doubt that a single (and simple) board computer like the Pi (even if it uses intel) will be able to handle a large, modern OS such as OSX. If you are interested in creating a non-Apple system that can run OSX, you should go to the Hackintosh Website. Unless you do some hacking (not the illegal kind), you will be unable to run it on any hardware other than one bought from Apple. It is based off of Unix, NextStep, and the original Mac OS. OS X is a proprietary OS used and created by Apple Inc. I may be wrong, but even Windows has a bit of Unix mixed in. Both are based on an old operating system called Unix, which is pretty much the mother of all OS's. OSX is compiled for Intel chips the Pi uses ARM chips. Yes, you do understand correctly - Raspberry Pi does not run OS X.

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