RGB: The additive color primaries: red, green, and blue.
CMYK: An abbreviation for Cyan (blue), Magenta (Pink/Red), Yellow, and Black. These are the four process colors a digital printer uses to create all other colors. Any artwork should be submitted in CMYK color format to avoid changes in color when printing.
Computer monitors use the RGB color model, but printers use the CMYK color model (which can reproduce most of the RGB color model). This is an importance difference, as the colors you are seeing on your computer screen may not be a 100% accurate representation of color when the project is printed.
If you are able to, we do ask that you convert all files to CMYK to ensure color accuracy as close as possible. You will likely notice a shift in colors when you do this conversion, usually making your colors a bit lighter.
If color is a concern for your project, talk to one of our team members to discuss getting a printed sample of your project before proceeding.
Learn more about how to convert RGB and CMYK colors here.