graphical user interface vs GUI

graphical user interface and GUI both are nouns.

Word	Noun	Adjective	Verb	Adverb
graphical user interface	Yes	No	No	No
GUI	Yes	No	No	No

As nouns, graphical user interface and GUI are synonyms defined as:

graphical user interface and GUI: a user interface based on graphics (icons and pictures and menus) instead of text; uses a mouse as well as a keyboard as an input device

graphical user interface (noun)	GUI (noun)
a user interface based on graphics (icons and pictures and menus) instead of text; uses a mouse as well as a keyboard as an input device	a user interface based on graphics (icons and pictures and menus) instead of text; uses a mouse as well as a keyboard as an input device