XPS M1530 Charger Issue

Hi Guys, my XPS M1530 charger gets really very hot. today one of my other friend bought a vostro 1510 laptop. i have just compared my charger with his charger. and these two r slightly different from each other. i mean mine one is bigger than his one. i should also add here that i have got 9cell betery. i have plugged his charger in to my laptop and it ofcourse works. so my question is why they r different even the main connector lid has got two pins (the cable which is connected from electric power circuit to bettery) where his one has got three pins.

so i m just thinking that if his one doesn't get so hot i should manage a charger like that one. any idea guys plz?