As much as the architectures are very similar you can't directly compare performance simply due to the clock rate ...
The manufacturing process of the Gamecube's processors was 180nm whilst the Wii's processors use the 90nm process; if the Wii used the same processors as the Gamecube the die size of the Hollywood and Broadway processors would be 1/4 the size of the Flipper and Gekko yet verified reports have the Hollywood and Brodway processor's die size at a little more than 1/2 that of the Flipper and Gekko.
The simplest (and most logical) explaination is that Nintendo has increased the number of transistors by adding cache and instructions to the Gekko to produce the Broadway processor whilst increasing the number of texture and lighting pipelines on the Flipper to produce the Hollywood processor.
The end result would be that added cache would increase the efficiency of the Broadway processor by lowering the number of times it has to go to general memory; the added texture and lighting pipelines on the Hollywood processor would enable it to process more texture data and lighting effects per frame.
