If you were to ask a Microsoft Sales Rep this question, they would no doubt have hundreds of tweaks and performance boosts from system to system. In reality however there are two main differences between the Windows Home edition and Windows Professional: Joining a domain and built-in encryption. Both features are active in Professional only, as joining a domain is nearly a mandatory requirement for businesses. EFS (Encrypted File System) in and its successor Bitlocker are both also only present in Pro. While there are workarounds for both of these items, they do present a nice quality-of-life boost as well as allow easier standardization across multiple systems. That being said, the jump from Windows Pro to Windows Server is a monumental paradigm shift. While we could go through all of the bells and whistles of what makes Windows Server…Windows Server, it can be summed up very briefly as this: Windows Home and Pro are designed to connect outwards by default and are optimized as such. Windows Server is designed to have other objects connect to it, and as a result it is optimized severely for this purpose. Windows Server 2012 has taken this to a new extreme with being able to perform an installation style very similar to that of a Unix/Linux system with no GUI whatsoever. As a result, they claim that the attack vector of the Operating System has been reduced massively (when installing it in that mode)