Discuss the difference between concurrency and parallelism in Rust.

In Rust, concurrency and parallelism are related concepts that deal with executing tasks concurrently, but they have distinct meanings and implications. Concurrency refers to the ability of a program to make progress on multiple tasks simultaneously. It allows different parts of a program to execute independently and concurrently, potentially overlapping in time. In Rust, concurrency can be achieved through various mechanisms, such as threads, async/await, or message passing between different components. Concurrency in Rust is facilitated by its support for lightweight threads called "green threads" or "async tasks." These threads can be scheduled and executed concurrently, enabling the program to make progress on multiple tasks at the same time. Rust provides a rich set of concurrency primitives and abstractions, such as channels, locks, and atomics, which allow safe communication and synchronization between concurrent tasks. ....