I haven't noticed any difference in color between my driver (autodim) vs passenger mirrors, but in terms of telling if it is autodimming, they have a black plastic surround at the edge of the glass.
My US w202 and Euro w210 autodim mirrors had this distinguishing feature.
Another "feature" of the autodimming glass is they turn transparent yellow when they age/fail. I suppose this is to make things higher contrast j/k. But my dealer tried to say this was not a defect. Which later i found it was.