The RODS detects shades of grey and are responsible for peripheral vision, while the CONES are responsible for colour vision and seeing fine details.
Rod cells are photoreceptor cells that are located on the retina of the eyes. Rods cells are usually concentrated at the outer edge of the retina and they are use in peripheral vision. Cones on the other hand are photoreceptor cells which are responsible for colour vision and they work best in bright light.