Hyperthreading

HyperThreading consists of duplicating the processor registers and pretending you have an additional processor (actually much less than a full processor). It appears to add about the equivalent of 1/3 of an additional "real" processor for much less space on the die than another full processor.

HyperThreading is what you do when you can't find any better ways to speed up execution.

The M1 architecture is already vastly more efficient. It does use a few IceStorm processors, which are extra low power, in conjunction with FireStorm processors, which are extra high performance.

Some possible reasons:

• Intel proprietary technology
• Different architecture
• Different language
• Not needed
• Energy inefficient
• Cache thrashing
• Older technology updated to "out of order" execution
• 2017 discovered that hyper-threading had a security issue
• 2019 Intel started moving away from hyper-threading in its mainstream processors
• Intel recommended disabling hyper-threading.

You may want to do some research yourself.