Here's a comparison
GeDoSaTo isn't used.
http://screenshotcomparison.com/comparison/99810 1600x900 native vanilla vs 2400x1350+4xSGSSAA (These are my screenshots).
Nothing is rendered at a lower resolution. It is simply just due to the rendering set up and the art style. (which includes the outlines.)
Even before release there were comparisons with the PS3 version showing that there indeed was a difference