redux-saga: call vs fork and join

Not that much as far as I can tell, but you can then cancel the task between the fork and the join.

const task = yield fork(api, arg);

if (someCondition) {
  yield cancel(task);
}

const result = yield join(task);

// Now a no-op since `join` blocked for the task to finish
cancel(task);

---

The difference is way bigger when you use spawn instead. It will create a detached fork that is not automatically canceled when the parent task is (for example).

In addition to @Pier's answer,

Both can be used to invoke normal and generator functions.

Also, fork(fn, ...args) perform a non-blocking call on fn - while call(fn, ...args) is blocking.

Example:

function* main() {
    yield fork(someSaga);
    console.log('this won't wait for the completion of someSaga');
}

function* main() {
    yield call(someSaga);
    console.log('this will wait for the completion of someSaga');
}

Here a useful example of fork.