This is fairly simply explained: * There is one unit of measurement, SAR * There are two maximum permissible values; one for the US, one for the EU * Apple has

This is fairly simply explained: * There is one unit of measurement, SAR * There are two maximum permissible values; one for the US, one for the EU * Apple has chosen the higher of the two so they can make a better phone (more power) * They get away with going over the US legal limit by recommending you hold it further away than normal It should be noted that not only are the max SAR values different for the EU and US but they are measured differently so can't really be compared directly.