When you install Windows Server 2012, you can choose between Server Core Installation and Server with a GUI. The Server with a GUI option is the Windows Server 2012 equivalent of the Full installation option available in Windows Server 2008 R2. The Server Core Installation option reduces the space required on disk, the potential attack surface, and especially the servicing requirements. In Windows Server 2012, you can freely switch between these options at any time, one approach might be to initially install the Server with a GUI option, use the graphical tools to configure the server, and then later switch to the Server Core Installation option.

To use PowerShell to switch between Server Core and Full Server with GUI

Full Server with GUI to Server Core

Uninstall-WindowsFeature Server-Gui-Mgmt-Infra -Restart

Server Core to Full Server with GUI

Install-WindowsFeature Server-Gui-Mgmt-Infra,Server-Gui-Shell -Restart