Server and Desktop Differences
There are a few differences between the Ubuntu Server Edition and the Ubuntu Desktop Edition. It should be noted that both editions use the same apt repositories, making it just as easy to install a server application on the Desktop Edition as it is on the Server Edition.
The differences between the two editions are the lack of an X window environment in the Server Edition, the installation process, and different Kernel options.
During the Server Edition installation you have the option of installing additional packages from the CD. The packages are grouped by the type of service they provide.
DNS server: Selects the BIND DNS server and its documentation.
LAMP server: Selects a ready-made Linux/Apache/MySQL/PHP server.
Mail server: This task selects a variety of packages useful for a general purpose mail server system.
OpenSSH server: Selects packages needed for an OpenSSH server.
PostgreSQL database: This task selects client and server packages for the PostgreSQL database.
Print server: This task sets up your system to be a print server.
Samba File server: This task sets up your system to be a Samba file server, which is especially suitable in networks with both Windows and Linux systems.
Tomcat Java server: Installs Apache Tomcat and needed dependencies.
Virtual Machine host: Includes packages needed to run KVM virtual machines.
Dynamic Host Configuration Protocol (DHCP) : is a network service that enables host computers to be automatically assigned settings from a server as opposed to manually configuring each network host.
Source and If you would like to get more information look this guide.