does anyone know if there is any difference between a platinum spark plug with a heat level 6 and an iridium with heat level 6 other than price and longevity. Are the heat levels actually the same and they are just made with different metals. I know there are differences in conductivity etc. but Im really interested in whether one is colder or hotter when rated the same.

 

The heat range is determined by the plug's ability to transfer heat. The small electrode doesn't have much to do with that ability...

so two different electrodes can have the same heat range.