What is the difference between color representation in RGB and CMYK?
Color representation on the screen: RGB (additive mixture of color stimuli)
Computer, laptop, tablet and smartphone screens work in the RGB color mode. What you see differs depending on settings (e.g. brightness, contrast, color temperature and calibration) and processing quality of the screen. In order to achieve color fidelity (like on print products), screens must be calibrated and profiled using a measuring device. Your program's output preview, also called soft proof, simulates the color result in printing.
Color representation on the print product: CMYK (subtractive mixture of color stimuli)
The color representation in the production of your print product also depends on the print substrate or material selected because different paper types have different characteristics. Recycled paper tends to have a grey-yellowish coloring while offset or art print paper can be more whitish or blueish.