What this isn't a guide at all.
Apple/Mac:
OS X:
OS X is commonly named after big cats like mountain lion. Although OS X commonly has updates the first version was released in 1999. It originally ran on PowerPC-Macs, but in 2006 Intel Macs could run OS X.
OS X V. 10.7 was the first version to have 32 bit and 64 bit Intel processors.
What is this?
"Commonly named after big cats"-- OSX has ALWAYS been named in that style.
"In 2006 Intel Macs could run.."--- WAT. Intel Macs could NEVER run the original OSX, the Intel Mac and Leopard were crafted together. What you mean to say is Apple introduced Intel processors and changed the architecture... but that still has no relevance to picking an operating system.