What is the difference between yielding a coroutine function call and yielding a startcoroutine call

Question

Unity coroutines can be chained together sequentially using something like the following

private void IEnumerator Outer()
{
    yield return StartCoroutine(Inner());
}

private void IEnumerator Inner() { yield break; }

However, the following also seems to do the same thing

private void IEnumerator Outer()
{
    yield return Inner();
}

What actually is the difference between the two methods, is one preferred over the other. I have only really seen the first in examples but the second has some really key benefits it seems (mainly not needing a monobehaviour to call StartCoroutine on)

Answer 1

快速谷歌搜索结果在这个线程中有很好的解释（IMO）。