Intel were x86, Apple Silicon is ARM-based. ARM-based chips are more power-efficient.

Also, it's built on a much smaller process. 3nm, if I'm not mistaken, older Intel was something bigger than 10nm. Heck, if you take a really old Intel Mac, you have something like 65nm process, which is much less efficient than 3nm.

Here's a random benchmark I found on the internet (literally the first thing on Google, you can find more if you want) https://www.cpu-monkey.com/en/compare_cpu-intel_core_i7_1065...