Which Datasheet applies to the ATmega328p? While researching minimum-voltage requirements of Uno, I came across what appear to be two datasheets for the ATmega328P:

http://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-7810-Automotive-Microcontrollers-ATmega328P_Datasheet.pdf

http://ww1.microchip.com/downloads/en/DeviceDoc/ATmega48A-PA-88A-PA-168A-PA-328-P-DS-DS40002061A.pdf

Specifically, the power requirements (and processor speed for each power level) differ. How could I know which datasheet applies to the chip I'm using? I'm actually using an Arduino clone:
You have ATmega328P-AU. Classic Uno with DIP socket has ATmega328P-PU. Arduino Uno SMD has Atmega328P-MU.

The automotive versions ATmega328P-15AZ and ATmega328P-15MZ have separate datasheet starting in Revision History with


  Creation of the automotive version starting from industrial version
  based on the ATmega48P/88P/168P/328P datasheet 8025F-AVR-08/08.
  Temperature and voltage ranges reflecting automotive requirements.