Tasks in Julia can make use of multiple threads and execute in parallel, whereas coroutines are confined to a single thread. Additionally, tasks are suitable for long-running and computationally intensive operations, while coroutines are more suitable for IO-bound tasks or cases where explicit yielding is required.

Both tasks and coroutines provide a concurrency model in Julia, but they differ in their execution semantics. Tasks are used for parallel execution across multiple threads, providing true concurrency, while coroutines are useful for managing control flow and avoiding blocking operations within a single thread. Each has its own purpose and can be used to solve different types of problems.

A task in Julia refers to an independently executing unit of code, similar to a thread. It can run concurrently with other tasks and allows for parallel execution. On the other hand, coroutines are lightweight cooperative multitasking units. They aren't truly concurrent but rather take turns executing, allowing for efficient scheduling of operations.