>I am curious about one thing: What are the major differences between IGBTs
>and MOSFETS? Lower Rds(on)?

In on state, MOSFET behaves like a resistor: Uds=I*Ron, P=Uds*I=Ron*I^2.
At the other hand, IGBT is like a saturated transistor, Uce is almost
independent of colector current: Uce=const, P=const*I. The advantage of IGBT
shows at very high current (talking hundreds of amps), and it can also
withstand higher voltages in off state.

Josef