With the introduction of Windows 8, Microsoft may have reduced the number of retail SKUs, but there are still many options compared with the single OS X installation. Selecting the correct version for running in Boot Camp or other virtualization solution is important.
John Rizzo at MacWindows says that the wrong version of Microsoft Windows 8 may not install in Apple's Boot Camp or in Parallels Desktop or VMware Fusion solutions. Or the version may be more software (and cost) than you need.
Read more at source: Picking the right Windows 8 for your Mac | ZDNet