P cores are conventional in that they can deliver excellent performance at maximum frequency, but with high power use. E cores may take 4 times as long for a task, but use less than a third of the energy.
Even though the M1 and M2 chips in modern Macs are based on ARM processor designs, they aren’t like any other ARM designs. That has made porting Linux to new Macs a difficult challenge, but there has been some impressive progress recently.
Apple revealed its first custom processor, the Apple M1, during an event in November 2020. The chip was met with high praise for cramming loads of power.