RGB and CMYK are two different color modes used in Adobe Illustrator for different purposes. RGB (Red, Green, Blue) is used for digital screens such as websites, apps, and social media because it creates colors using light. CMYK (Cyan, Magenta, Yellow, Black) is used for print designs because it works with ink mixing on paper. Choosing the correct color mode ensures accurate color output—RGB for screen-based designs and CMYK for printed materials like brochures, posters, and business cards.