As ScoRp!oN sez, and was clearly stated in the beginning of the comparison, the texture compression being on by default for the GTS might explain its lesser visual quality but in the conclusion the Radeon beat the GTS in smoothness despite that the texture compression should have been an advantage (my reasoning) so the Radeon is better.
"Finally, although this is not related to image quality, but is an interesting comment on how the Radeon does on the NV15 level, which was released by NVIDIA. This level looks to stress video cards by tossing all sorts of visual effects at the card (which chew up gobs fill rate) as well as encorporating structures with high polygon counts. Basically, this demo suits the two strongest assets of the GeForce2 - an amazing 1.6Gtexel/sec fill rate and 25 million triangles per second hardware T&L engine.
It is surprising indeed then that the ATi Radeon runs this level better than the GeForce2 card. At the High Quality detail settings we used, the GeForce2 stuttered quite noticeably and did not deliver a smooth framerate. Comparitively, the Radeon's performance was silky smooth - a surprising result indeed."