Well, you can easily tell who's who by their color (XBox=Green, PS3=Black, Wii=White), or by their name, in the case of the human characters (I
(ile Heart), the companies who made the games).
And, actually, as the name implies, the main characters are actually the Sega representatives.
(Did I mention Sega distributed the first two games in Japan?)(Though, funnily enough, the PS3 character is the most popular character in the series, to the point she will be getting her own game)