The answer to this is the cone cell. If you are not too familiar with this, this is a type of cell found in the eye that will usually respond to the various wavelengths of light differently. This explains why we can determine that there are different colors. This type of cell works best under bright light.
Some people have problematic cone cells that are unable to process the various wavelengths of light. This can result in color blindness. Men are more prone to this condition more than others. The different cones of the eyes are more sensitive to red, blue, and green colors as compared to the other colors that we can find.