MCPatcher ... helps you to switch easily and fast to almost every Minecraft version provides over 100 Minecraft versions (provided you have bought the game) can be used to change your Minecraft version via shortcut provides the ability to change to your collected Minecraft versions on the fly can detect your Minecraft versions and whether you can use HD-Texture packs or not works offline creates a backup before changing the versionIn addition lots of patched versions do directly support HD-Texture packs!MCPatcher only contains the most important minecraft versions,while MCPatcher Pro contains nearly all Minecraft Versions.So which one is the best for you? Therefor just think about which version you want to play.If you just want to switch between for example 1.5.1 and 1.4.7 then you should use MCPatcher.If you want to play versions like 1.4.3, because you want to take advantage of a bug in it, you should download MCPatcher Pro.