maximized window ≠ full screen
in Maximized state the window is set to maximal available size (so you are not wasting any part of the screen) while you are still provided with fast and easy access to relevant OS UI elements
in full screen you explicitly tell the system that you don't want to be distracted by OS UI elemtents (typically in situation when you know that you won't need them for extended period of time, or if you REALLY need every single pixel of the screen)