The folks at a game development company Distinctive Developments have posted a cool video comparison of the Nexus One and iPhone 3GS. In the video they compare the 3D performance (GPU -Graphics Processing Unit) of the two phones. They render the same game scenes on both the phones and test the frame rate and graphics. As you can see in the image below, the 3GS is doing 60 frames per second and the Nexus One is doing 31 frames per second.
httpv://www.youtube.com/watch?v=GYqZK25KU3U&feature=player_embedded
One of the main reasons for the lower frame rate on the nexus one might be the larger screen size. The GPU needs to fill 2.5 times as many pixels on the Nexus One than it does on the iPhone.
In this test the 3D engine code running on both devices is the identical with one major exception – the Nexus isn’t using Neon floating-point optimization
Even though the iPhone 3GS packs only a 600Mhz CPU compared to the Nexus One which packs a 1 GHz CPU, the iPhone wins in the 3D arena. The Nexus One is powered by Android which is not yet fully optimized for gaming and 3D applications like the iPhone according to this test.