Twenty years ago was 2001: the days of Photoshop versions 6.5–7. The Mac (OS 9) and Windows (2000) versions were all but indistinguishable, and Apple had just released OS X which was still a slow and buggy mess, not yet used by creative professionals.

If you said Photoshop 3.0 was clearly better on Mac System 7 than Windows 3.1 in 1994, you might have a point (that was before my time using Photoshop or Windows, so I can’t comment).