Because IIS is integrated into the Windows operating system, many of the changes to IIS 8.0 have to do with changes to the Windows operating system itself. Windows Server 2012 has many new features that affect and enhance IIS 8.0.
Windows Server 2008 came in multiple versions, including Standard, Enterprise, and Datacenter, primarily differentiated by the amount of memory and number of processors accessible. Each was targeted, and licensed, for specific deployment types, and changing the version required a full reinstall.
Windows Server 2008 also had several special editions available. Windows Server 2008 Web Edition was designed to run a web server but could not run applications such as Microsoft Exchange or be used as an Active Directory server. The HPC Edition was designed for high-performance computing, using computing clusters and expandable into a Microsoft Azure data center for cost-effective high-performance tasks. Windows Server 2008 was also available for Itanium processors and also in a Foundation version for the low-cost and low-performance server needs of small companies.
Windows Server 2012 will not support 32-bit or Itanium processors. There is no longer a Web Edition or Foundation version, and the features of the HPC version have been incorporated into the standard operating system. In short, you can buy Windows Server 2012 in only one edition and install it for any system configuration you need, physical or virtual. ...