The Windows beta mascot, the Betta Fish, is as much part of Windows Server 8 as it is the desktop version.
There are two installation options for Windows Server 8: Server Core or with a GUI. If you install a GUI you can remove it later — either all the way down to Server Core or as a new minimal UI Server.
Metro, or at least the Metro design language, is everywhere in Server 8. You'll find it in the logon screen, with an attractive deep blue background and white text.
The UI-less Server Core is Microsoft's preferred installation for Windows Server 8. It's more secure, and doesn't have the overhead of a full GUI.
Server Manager is the heart of Windows Server 8. It's where you'll set up and manage both local and remote servers, with tools for managing groups of servers and giving you an at-a-glance view of issues and problems.
You can add features and roles to both local and remote servers from the Server Manager. Just choose what you need to install, and Windows Server will install the appropriate packages.
You can install and run Metro applications on Server 8, with a Metro-style Start Menu replacing the old start orb. As in the Windows 8 client, you click in the lower left corner of the desktop or press a Windows key to open the Start screen.
Windows Server 8's Storage Pools let you build massive virtual storage arrays from commodity hardware, with thin provisioning and support for the new ReFS resilient file system.