4x20 alphanumeric LCD with backlight.
Backlight is efficient 4 .. 4.2 V drop (most often 22 or 27 Ohm resistor is used to limit backlight current from 5V).
4x20 is the only maintained geometry in VEMS v3 firmware therefore the recommended size.
The blue LCD has somewhat smaller form-factor (narrow as the LCD itself: solder pads on the side) => fits into places where the green or red does not
Note: if certain color is not (at the moment) available, it might still be available as