Thermal Guideline ?!?! help explain this please.

I am here

On Intel's Processor Spec Finder
http://processorfinder.intel.com/scripts/list.asp?ProcFam=483&PkgType=ALL&SysBusSpd=ALL&CorSpd=ALL

I notice

Thermal Guideline
SL6WR - D1 - Thermal Guideline 66.2W - Thermal Spec 74°C
SL6WF - D1 - Thermal Guideline 66.2W - Thermal Spec 74°C
SL6Z3 - M0 - Thermal Guideline 75.1W - Thermal Spec 72°C

I thought That if the Thermal Guideline is lower thanthe CPU should be cooler.
How come the M0 Stepping is the coolest and it shows a HIGHER Thermal Guideline.

Can someone explain what "Thermal Guideline " and "Thermal Spec " explain mean ?

Thanks In Advance.

Thermal guideline is the amount of power (heat) that the processor is expected to put out, and thus the amount of heat that the cooling solution needs to remove from the chip.

Thermal spec is essentially the maximum safe operating temerature for the processor in a system.

Those two terms are similar to (though not always exactly the same as) TDP (thermal design power) and Tcmax (maximum case temperature).

I am just wondering because I know the M0s run a little cooler and overclock better how come there Thermal Guideline is 8.9Watts more?