Here’s a side by side comparison of all four iPhone generations. The original iPhone is running 3.1.3, the 3G 3.1.2, the 3GS 4.01 and the iPhone4 was running 4.0.
Speed Comparison: iPhone 2G vs 3G vs 3GS vs 4 [video]
Here’s a side by side comparison of all four iPhone generations. The original iPhone is running 3.1.3, the 3G 3.1.2, the 3GS 4.01 and the iPhone4 was running 4.0.