The fine points of various Mediatek SOC's

My last purchase of Panasonic P75 was a bit puzzling for me when I checked out the soc name and the specs. Point was, the soc was mentioned everywhere as MT6580. But my previously purchased phone Panasonic T44 also has the same soc. Plus the same specs, but when I used both the phones I could clearly tell which one was faster and which one was slower. 

As I saw in daily use Panasonic P75 is definitely faster, smoother etc with same 1GB of RAM, with same soc clock speed of 1.3GHz. So what's wrong?

Turns out the soc info for the cheaper phone was incorrect. It has MT6580m soc. This is what's a watered down version of MT6580. And so this is what's causing the difference in performance. Since from what I saw in actual usage - the mt6580 is faster so Android is smoother there as compared to mt6580m which feels only adequate. 

Ciao.