This is a simple question for others, but I'm still a little confused
Hello.
They are related, but I would separate them like this:
CPU architecture defines the hardware... how the processor works. This includes basic things such as how values are calculated, to more device specific things, such as how exceptions are handled, or how the memory is partitioned.
The Instruction Set Architecture (ISA) defines the software - that is how the CPU is programmed to do what it can do, and in the appropriate order.
The below links may explain more:
https://www.arm.com/architecture/cpu
https://www.arm.com/glossary/isa
Thank you for your answer, so microarchitecture is also defining hardware, right?
Yes, microarchitecture describes different implementations of the same architecture.
For example, different pipeline lengths of the Cortex-M3 vs Cortex-M7.
Thanks for answering my questions.