User blog comment:Kogath/Monster Hunter: World Discussion/@comment-6050823-20190728081447/@comment-6050823-20190729175246

He's talking about how the Raths, and some other monsters like Diablos, vary from region to region (Pretty much the lore reason why some older monsters are different from each other from game to game). Some of them are more major than others like when you compare 1st - 2nd Gen Raths and Diablos to the 3rd Gen ones, or, more recently, the 3rd Gen to 5th Gen incarnations.