For both x86 architectures (64bit and 32bit) and editions (Standard, Enterprise and Datacenter) there’s a “Without Hyper-V” Stock Keeping Unit (SKU) and a SKU that includes the Hyper-V technology. What’s the difference between these versions?

Microsoft describes Windows Server 2008 without Hyper-V as:

For customers that do not need virtualization, Windows Server 2008 Standard, Enterprise, and Datacenter editions are available without Windows Server Hyper-V Technology.

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Further Reading

• Windows Server 2008: Editions without Hyper-V 
• Why is there a 32-bit Windows Server 2008 option "without Hyper-V"? 
• VMWare Forums - 2008, with or without hyper-v? 
• Eggheadcafe - Add RTM Hyper-V to 2008 "Without Hyper-V" 
• Vista Forums - Role Hyper-V on windows server 2008 
• Microsoft TechNet Forums - unable to install hyper-v roll on 2008 core  
• Microsoft TechNet Forums - Hyper-V Server Management Tools.