Adams insight XTD,RPM,GT500 differences?

[YamahaJay]

I was recently shopping for a new set of cheaper beginner irons,although I'm not a beginner I still golf like one. I ran across the Adams RPM's,Insight Xtd's and GT500s. I have read somewhere the RPMs are Extreme forgiveness and the GT 500s are forgiving but not quite as easy to hit as the RPM's. I ended up purchasing the Insight Xtd's which look identical to the RPM's in shape. I am thinking that Adams branded some clubs Insight Xtd for some suppliers(Dicks sporting goods) and RPM's for others(Dunhams Etc.). Does anyone know for sure the differences in these clubs? The sales guy at Dicks pro shop said he doesn't even list the RPM clubs in the Adams catalog but they look just like the RPM's to me.Just looking for some clarification by someone who might know.