CPU frequency is the clock speed of the processor. The bus speed is the clock frequency of the bus which connects the processor with the RAM and the chipset.
CPU frequency is not the measure of the performance of the CPU. Pentium 4 were _base_d on NetBurst architecture which wasn't a good architecture, so even with high frequencies it didn't yield much performance, whereas the new Core architecture with high-k transistor gates is very efficient, so it yield more performance per Mhz.
Increasing the bus speed also increases the CPU frequency since they are _link_ed together. It also increases the frequency of the RAM.
