How do ES modules differ from CommonJS at the engine level — live bindings vs value copies, static analysis, circular dependency handling, and top-level await?

Think of modules like toy boxes. CommonJS gives you a copy of each toy, so if someone changes their toy, your copy stays the same. ES modules give you a window to the toy box, so you always see the real toy, even if it changes. Also, ES modules can wait for a toy to be ready before playing, like waiting for a friend to arrive.