There's not really a reason (other than Game Freak getting lazy), and probably wasn't intended to look that way, but they are sort of similar; you could say that. The colors are certainly similar, so I can see why you'd think that. Do keep in mind though this happens a lot; back when we didn't know much about Unova's new Pokemon, many of us believed that Alomomola was an evolution on the pathetic Luvdisc.