well,, one is a manual step, versus the second is an automatic step, so,, even though the light meter is happy, the auto step will exposure at a different shutter speed than what would have been the calculated one, versus looking thru the camera and in manual mode, applying the compensation and viewing the light meter bar + or - depending upon the direction. Personally, I prefer to manually control the exposure versus depending upon the auto compensation, because then I forget to change it back, and next time out, under or overexpose a picture (just like when I forget to turn off bracketing).