Yes, it changes rasterization. It’s because MacOS has a legacy of dilating the pixel outlines when subpixel antialiasing is enabled.
When subpixel antialiasing first appeared on OS X, the FIR filter affected the gamma curve, making the font seem too light or thin. Correcting gamma the right way was expensive at the time, so they changed the rasterizer to dilate the outlines, increasing the contrast of the text.
At that same time, the *nix APIs like Xft just cranked up the coefficients of the filter so that the sum was ~40% higher than it was supposed to be, which also worked. I think that was a better method than sabotaging the outline shape.