The Red / Blue versions were made for the Original Gameboy that was monochrome. Yellow version was made for the Gameboy Color; however, it did not get the full pallet that was available on the GBC. It was made so that those that have not purchased a GBC could play it on the Original Gameboy (in monochrome). Although some maps are the same, below is representing all maps in the original color (labels are in color for emphasis).