Difference between a “coroutine” and a “thread”?

Question

What are the differences between a \"coroutine\" and a \"thread\"?

Answer 1

Coroutines are a form of sequential processing: only one is executing at any given time (just like subroutines AKA procedures AKA functions -- they just pass the baton among each other more fluidly).

Threads are (at least conceptually) a form of concurrent processing: multiple threads may be executing at any given time. (Traditionally, on single-CPU, single-core machines, that concurrency was simulated with some help from the OS -- nowadays, since so many machines are multi-CPU and/or multi-core, threads will de facto be executing simultaneously, not just "conceptually").