I WANT TO KNOW ABOUT VGA DIFFERENCE PLEASE?

IF I HAVE TWO TYPES OF VGS CARD MEANS PCI AND AGP OF SAME CAPICITY WHICH ONE IS FASTER AND THEY HAVE SAME ALL SPECIFICATION I WANT TO PLAY GAME HEAVY GAMES WHICH IS BETTER FOR ME THEY ALL 4.0 SHADER SUPPORTING AND 512 MB PLEASE HELP ME PLEASE AS QUICK AS POSSIBLE PLEASE