This is Rob's perspective, but it's not universally shared. In my mind, all concurrency is a form of parallelism (parallel tasks, but not parallel threads) while not all parallelism is concurrency. I have frequently solved concurrency problems with thread pools, rather than using non-blocking IO, because the programming paradigm is a lot simpler.

You got the the wrong way round: all parallelism is a form of concurrency.

In Python, thread pools and async work mostly the same in practice, except that threads have a bigger overhead. So they can be used to solve the same problems.