Hello Seek -
I also have the integrated plastic mirrors on my Sprinter. My guess is that the integrated plastic ones, like mine, are electrically adjustable from within the cab while the metal bar mounted ones are only manually adjustable by hand out the window.
Does that match with your experience?
Mine adjust quite well electrically and then can be adjusted to either 2 or 3 positions manually as well as can be knocked forward or backward, if I remember correctly, when something strikes them, and then pushed back into the correct positions by hand.
Zach