“RGB” stands for “Red Green Blue”, which is used in monitors. “CMYK” stands for “Cyan Magenta Yellow Black-(K)” which is used in press in multi-color printing. When RGB colors are combined, it creates white color, meanwhile if CMYK colors are combined, it creates black color. You may notice the difference in color if you do the process of changing color mode yourself. Hence, it’s impossible for the press to exactly match the colors as seen on the screen.