MDA = Monochrome Display Adapter (text only) https://en.wikipedia.org/wiki/IBM_Monochrome_Display_Adapter
CGA = Color Graphics Adapter https://en.wikipedia.org/wiki/Color_Graphics_Adapter
EGA = Enhanced Graphics Adapter https://en.wikipedia.org/wiki/Enhanced_Graphics_Adapter
VGA = Video Graphics Array https://en.wikipedia.org/wiki/Video_Graphics_Array
With some others like the Hercules which was MDA upward-compatible and did graphics as well as text.
They didn't really do any graphics "processing"; just displaying memory-mapped pixels in various formats.
They were memory-mapped, and the MDA used a different memory block than the CGA/EGA/VGA, so you could have two separate monitors simultaneously, doing things lke running something like Turbo Debugger on the MDA text display.