Final answer:
The main difference is that SAR (Specific Absorption Rate) measures the RF energy absorption by the body from devices like cell phones, with the FCC requiring a maximum SAR level of 1.6 W/kg for cell phones in the U.S., while SAA has different meanings unrelated to this context.
Step-by-step explanation:
The main difference between SAR and SAA lies in their definitions and fields of application. SAR, which stands for Specific Absorption Rate, is a measure used to quantify the amount of radio frequency energy absorbed by the body when using devices like cell phones. The Federal Communications Commission (FCC) mandates that the SAR level for a cell phone sold in the United States should not exceed 1.6 watts per kilogram. In contrast, SAA could stand for multiple things, but none relate to Specific Absorption Rate as closely as System Acquisition Analysis or System Analysis and Assessment, neither of which are relevant in this context of measuring RF energy from cell phones.