The color and brightness emitted by an LED are determined by the chemical composition and construction. Single-color (monochrome) displays are made up of one color of LEDs, whereas full-color displays contain LEDs that emit red, green and blue light. The color efficiency of the human eye has different sensitivity to different colors, and therefore perceives the brightness of each color differently.
The number of LEDs alone does not determine display brightness. The design, quality, brightness, lens and viewing angle of the LEDs, as well ad the drive method and contrast of the module, determine the overall brightness of a display. In fact, using more LED’s per unit area creates more hear and therefore requires more cooling.