While CMYK and RGB are two of the most prominent color models used, there are many differences between the two.
CMYK is a four-color mode that utilizes the colors cyan, magenta, yellow and black in various amounts to create all of the necessary colors when printing images. It is a subtractive process, meaning each additional unique color requires more light is removed or absorbed, to create colors. When the first three colors are added together, the result is not pure black, but rather a very dark brown. The K color, or black, is used to completely remove light from the printed picture, which is why the eye perceives the color as black.
RGB is the color scheme that is most often associated with electronic displays, such as CRT, LCD monitors, digital cameras and scanners. Contrary to the CMYK method, RGB is an additive type of color mode that combines the primary colors, red, green and blue, in varying levels, to create a variety of different colors. When all three colors are combined and displayed to their full extent, the result is a pure white. When all three colors are combined to the lowest degree, or value, the result is black. Software such as photo editing programs use the RGB color mode because it offers the widest range of colors.