The display contains its own controller driver chip with a character map built into the IC. The character map makes it easy for the design to integrate their software, aka firm ware, into the pre-written software of the LCD module. When the engineer wants to display the letter 'A', all they have to do is send a command requesting the capital 'A'. This is much easier than a graphics LCD module where each dot on the letter 'A' needs to addressed. This is a very time consuming activity.
