In the Server Core installation, the initial server payload can be pre-configured to wake-up the first time and find resources as a package, or can be rapidly and subsequently built through the use of additional PowerShell commands (in the form of text-based scripts) to get the server initially configured. If you haven't preconfigured anything, you're dropped to a CMD box at the end of the Server Core installation, and will subsequently run administration and modification of that server from a different machine, or through the use of PowerShell cmdlets -- perhaps a favored set of scripts completes the provisioning process for the server.
If the GUI-based installation is chosen, only a few selections need to be made until the server initially comes alive. From there, a server installation dashboard provides choices of what to do to install additional features. We could flip away from there and get a Windows 8-ish UI that allowed us to do things like set initial IP configuration, and perform other Control Panel settings. When we flipped back to the dashboard, we then made our installation choices.
When we wanted to install features, we could do so as traditional Windows Server "Roles" into the current server, a group of servers (where that makes sense), or tuck them with various pre-configuration steps into a Virtual Hard Disk (VHD file). Of the installation choices, one can add components like the IIS web services, Active Directory, or the AD Rights Control Services, along with print and other familiar services.
What we liked about the changes in the Dashboard approach was that it allowed us to make choices, and it would figure out the dependencies -- other apps needed -- then let us allow the server to reboot automatically if we desired (rather than get hung up waiting for us to click "ok" when each server Role was installed). The Server Core version does the dependency checks, too.
This varies significantly from Windows 2008 R2 Server and former Windows Server editions, and comes closer to the ease of configuration found in dependency-checking apps from SUSE (YaST), and other RPM/like managers found in Red Hat Linux distributions.
Roles now included are Active Directory Certificate Services (upgraded from the CA Role in 2008 editions); Active Directory Domain Service, Active Directory Federation Services, Active Directory Lightweight Directory Services; Active Directory Rights Management Services (new), Application Server; DHCP Server; DNS Server; Fax Server; Hyper-V (installs the hypervisor and/or manager); Network Policy and Access Services; Remote Desktop Services; Volume Activation Services; Web Server (IIS); Windows Deployment Services; and Windows Server Update Services (WSUS).