oh come on, there's no difference between the two, except for the OS. Hardware upgrades on a mac aren't that hard and the units run faster than their PC equivalents- why else would you be able to run windows on top of the Mac's OS at comparable speeds to a PC itself.
Doing the actual upgrade for a Mac isn't hard... finding the hardware you want can be. As the picture illustrates, you literally have unlimited choice in hardware when you build a Windows box. With a Mac, not so much. There's nothing special about the Mac hardware... it's not running any faster than if it were running Windows.