What is the difference between Eggman and Eggman Nega

Well, Eggman and Eggman Nega have only a few differences mainly with their moustache color and clothes. It appears that Eggman's skin color is a bit lighter. While Eggman's costume scheme consists of red black and white, Eggman Nega's costume consists of yellow black and white. Eggman Nega's moustache is grey while the original Eggman has a brown or orange moustache(Color of his moustache varies on certain games). This fools some fans into believing that Nega is either older or they also think that he is Eggman's uncle.