Parallelism is an implementation property. Parallelism is literally the simultaneous physical execution of tasks at runtime, and it requires hardware with multiple computing resources. It resides on the hardware layer.
Back in the kitchen, now we have two chefs, one who can do stirring and one who can chop the salad. We’ve divided the work by having another processing resource, another chef.
Parallelism is a subclass of concurrency: before you can do several tasks at once, you have to manage several tasks first.
