I like to think of them as different levels. Concurrency is at a higher abstraction level: steps that can execute without needing to wait on each other. Paralle

I like to think of them as different levels. Concurrency is at a higher abstraction level: steps that can execute without needing to wait on each other. Parallelism is a bit lower and reflects the ability to actually execute the steps at the same time. Sometimes you can have concurrent units like multiple threads, but a single CPU, so they won’t execute in parallel. In an environment with multiple CPU they might execute in parallel.