Windows Server 2008 comes in several major editions derived from the same code base. The most important differences among editions are in the number of processors, amount of physical memory, and high-availability features supported.
The edition specifically targeted at servers with Itanium CPUs, Windows Server 2008 for Itanium-Based Systems (IA64), is not listed in the chart, but its features and price are almost identical to the Datacenter Edition listed in the rightmost column.
| Windows Server 2008 Web Edition | Windows Server 2008 Standard Edition | Windows Server 2008 Enterprise Edition | Windows Server 2008 Datacenter Edition | |
| Supersedes | Windows Server 2003 Web Edition | Windows Server 2003 R2 Standard Edition Windows Server 2003 R2 Standard x64 Edition | Windows Server 2003 R2 Enterprise Edition Windows Server 2003 R2 Enterprise x64 Edition | Windows Server 2003 R2 Datacenter Edition Windows Server 2003 R2 Datacenter x64 Edition |
| Hyper-V virtualization technology | Not included | Included1 | Included1 | Included1 |
| OS instances permitted per server license | One instance (physical or virtual) | One physical instance plus one virtual instance2 | One physical instance and up to 4 virtual instances2 | Unlimited number of OS instances |
| Maximum server RAM supported3 | 32-bit: 4GB 64-bit: 32GB | 32-bit: 4GB 64-bit: 32GB | 32-bit: 64GB 64-bit: 2TB | 32-bit: 64GB 64-bit: 2TB |
| Maximum number of CPUs | 4 | 4 | 8 | 64 |
| Hot swap RAM and CPUs | No | No | No4 | Yes |
| Cluster Service (failover) | No | No | Yes, up to 16 nodes per cluster | Yes, up to 16 nodes per cluster |
| Terminal Server | No | Yes5 | Yes | Yes |
| Network Access Protection | No | Yes6 | Yes | Yes |
| U.S. estimated retail price7 | US$470 per server ( available only without Hyper-V) | US$800 per server (US$772 without Hyper-V) | US$3,000 per server (US$2,972 without Hyper-V) | US$3,000 per processor (US$2,972 per processor without Hyper-V) |
| CALs or External Connector required8 | No | Yes | Yes | Yes |
1 Windows Server 2008 Standard, Enterprise, and Datacenter are also offered in “without Hyper-V” editions that do not include the hypervisor technology.
2 When customers exercise the maximum number of OS instances permitted by the server license, the physical OS instance may not be used to run any workload beyond hosting the virtual machines.
3 A single package contains both 32-bit and 64-bit versions. The server license grants the customer the option to use either the 32-bit version or the 64-bit version of the software.
4 Supports hot addition of memory, but not hot replacement of memory, nor hot add or replacement of processors.
5 Use of Windows Server 2008’s new Terminal Services Gateway capability is limited to 250 connections.
6 Includes restrictions limiting scalability.
7 Volume licensing customers typically receive additional discounts of 10% to 30%.
8 Client Access Licenses (CALs) retail for US$40 apiece but are offered to volume customers for as much as 50% off. External Connectors are available only via volume licensing programs. Pricing for an External Connector starts at approximately US$1,800 in the least-discounted programs.