While power draw can't be measured in an AWS instance, there's no particular reason to suspect there's anything all that interesting here. Other ARM 64-80 core chips have the "normal" ~200W TDPs you'd expect to find in server CPUs of this type, and there's been very little difference in general power efficiency between ARM & x86 for many years now. ISA doesn't matter much here, it's more about the target design & performance the chip is trying to hit.