the iphone doesnt have a dedicated 3d graphics chip like the droid. the iphones "graphics chip" on the iphone 4 is a layer on the cpu that renders the graphics of the os. the older iphones do have a dedicated graphics chipset, but it is nowhere near as powerful as the droids. if you remember way back in android 2.0 and 2.0.1 the droid's 2d framerates would easily hit 60 fps in fps2d even clocked at 600mhz but its been severely limited to save battery life etc...
the iphone doesnt have a dedicated 3d graphics chip like the droid. the iphones "graphics chip" on the iphone 4 is a layer on the cpu that renders the graphics of the os. the older iphones do have a dedicated graphics chipset, but it is nowhere near as powerful as the droids