setTimeout VS web worker - when to use what?

Question

Both setTimeout and web worker more or less do the same thing. They make the main thread non-blocking and does it's work asynchronously in the background. How do we judge when to use what?

Answer 1

They make the main thread non-blocking and does it's work asynchronously in the background.

No. They don't. That's what a Web Worker does.

setTimeout puts a function on a queue to be run later. When it runs it still runs on the main thread and is just as blocking.