In a command line interface, the user types commands using the keyboard to tell the computer to take an action. For example, the more command available in most operating systems will display the contents of a file. Sometimes people call CLI “Console”, but consoles can be GUI, too.
Graphical user interfaces are generally thought more easy to use than command lines. Command lines are faster than graphical user interfaces and can be used to give special commands to the computer.
List of operating systems with graphical user interfaces and command-line interfaces:
Graphical user interfaces and consoles Facts for Kids. Kiddle Encyclopedia.