nothing, unless its from a certain manufacturer. If the same manufacturer has two different colors then its usually because of different strengths of the same compound. Now if its U.G. Lab, it could be any color and any shape. They were selling superman pills with the superman logo on it.
Color has no meaning. At the same time some manufractures do have different colors for different mg's per pill. I know that British Dragon makes pink 50 mg's and another company makes 5 mgs blue hearts and 5 mg pinkies.