This document will be based on the ARMv8-A architecture, mainly focusing on AArch64, and comparing it to ATmega2560's megaAVR architecture.
Thus "ARM" will be used to mean "ARMv8-A AArch64" and "AVR" as "megaAVR".
Microarchitectural details for ARM are taken from the Cortex-A57.
Focusing on the differences between ARM and AVR, ARM has: