1066mhz front side bus? sounds really high? how does that work?

ok so, i've looked into overclocking, and i see the clock speed you change in the bios is somewhere around 300-500mhz, people call this the front side bus, but when i buy a processor, i see 1066mhz or 1333mhz. what's the difference in those speeds? on a side note, why does amd have like 1800mhz and 2000mhz "fsb" where intel h up to 1600mhz, why, and are they different?