Powersave keeps it at lets say 800mhz under any load
Ondemand lets it sit at 800mhz, but kicks it up to MAX (for me 1.6ghz) immediately under any load to get it done as fast as possible.
Conservative sits at 800mhz, and when a load hits gradually kicks the frequency up by one step (I think a step on intel is like...50mhz? I could be totally wrong on that though) until the load is done, then it drops it back to 800mhz.
Conservative helps temperature because you're only ever gonna hit max frequencies if its a sustained load in which case you probably WANT maximum frequency, otherwise you're sitting around middle frequency. Lower frequency = lower temperature.
And yeah LAB is like turbo boost.