Question

how is CUI differ from GUI operating system

Answer 1

CUI means command user interface i.e it uses commands to work and GUI means graphic user interface i.e it uses graphics like pictures, media,etc to work.

Answer 2

CUI = Character User Interface = like a DOS prompt, you just type in commands and results are displayed in text  GUI = Graphical User Interface = like Windows, you have lots of pretty things to look at, more colours, and probably a mouse to control the cursor....it's supposed to be more user-friendly because it is more intuitive, i.e. People will find it easier to figure out how to click on something than trying to remember lots of commands and parameters and stuff.