GUI (Graphical user interface) or CLI (command line interface) ? what should i use?

The operating system offers to users two kinds of usinf : a GUI & CLI interface.
so that the user can interact with the electronic device or product. some operating systems provide GUI and CLI while others offer only CLI.
GUI means Graphical user interface while CLI means the command line interface.
As its name sense, one has to write commands to do or achieve a certain task in the CLI system, while GUI offers graphics that represented as icons and images that allows to a user to do his tasks directly with mouse. CLI requires expertise in commands and little bit of programming and dealing with developement flow for performing a certain task while GUI can be used by all (beginners and experts).

GUI works with computer graphics .
One can click on the icon; drag the object with help of mouse. There is no need to remembering commands in this. GUI comes with numerous components. With the help of a textbox editor, one can enter input data in this. A menu offers a list of options to choose from. Buttons enable the user to select a particular option. The checkbox element enables the user to select an option to choose from multiple alternatives. Linux and Windows use a Graphical User Interface. It consists of icons, windows, menus, pictures and many other graphical elements.

Command language interpreter, Character User Interface, and console user interface are some different names of the command line interface. In this system first, the user enters the commands and presses enter to execute that command. In this way, the user can interact with the device. It is important to have correct knowledge of syntax to give effective commands. An operating system lile UNIX has CLI While an operating system like Linux and windows have both CLI and GUI.
To become a professional developer, it recommended to use command line, because in development environement you will not use the graphical interface.