Both cards have same number of pixel pipes, but the GS's core clock is in the 400 MHz range while the GT's core clock is stock at 560 MHz, with many vendors pushing that to around 600. Memory clock is another area where the GS suffers, using much slower GDDR2 versus the faster GDDR3 found in the GT. While both versions may have 256mb of VRAM, the GT's RAM is clocked stock at 1400 MHz (with some vendors pushing that to nearly 1600), while the GS's RAM is clocked at a rather conservative 800 MHz stock.