std::sync blocks threads for concurrency, while tokio::sync yields control to async runtimes for non-blocking operations.
std::sync provides blocking primitives for multi-threaded programs, while tokio::sync provides non-blocking primitives for async runtimes. Use std::sync when you need to block a thread until a resource is available, and tokio::sync when you need to yield control to an async runtime without blocking.
use std::sync::Mutex; // Blocks the thread
use tokio::sync::Mutex; // Yields to the runtime
std::sync tools stop your program's thread until a task is done, like waiting in a line. tokio::sync tools let your program pause and do other work while waiting, like checking your phone while waiting for a bus. You use std::sync for regular multi-threaded code and tokio::sync for async code that needs to handle many tasks at once.