Color theory, or more specifically traditional color theory, is a historical body of knowledge describing the behavior of colors — namely in color mixing, color contrast effects, color harmony, color schemes and color symbolism. Modern color theory is generally referred to as color science. While they both study color and its existence, modern or "traditional" color theory tends to be more subjective and have artistic applications, while color science tends to be more objective and have functional applications, such as in chemistry, astronomy or color reproduction. However, there is much intertwining between the two throughout history, and they tend to aid each other in their own evolutions.
Though, color theory can be considered a science unto itself that uses the relationship between human color perception and the interactions of colors together to build their palettes, schemes, and color mixes. Importantly, color theory relies upon objective standards in-order to be consistent in color mixing and presentation - i.e. to achieve the ideal color and effect, your ratios of colors must be consistent and often exact. As for functional applications, color theory intandem with color science is what allows humans to achieve ideal camouflage, designed paints that disperse more heat, and is often used by theme parks like Disney to achieve their ideal aesthetic.
