Are you referring to the fact that some of the text looks slightly "straight" on edges on one version and not on the other?
This is a perception thing.
Pixel-wise, it's exactly perfect.
I've inverted the image you gave us so that the black on white text is now white on black and vice versa, and the same effect appears on the one on white (the one that looked fine before).
I'll upload the image. It has your screenshot at the top, and the inverted version at the bottom.