Difference: yield WaitForFeconds() vs yield return new WaitForFeconds()

The question is simple. Regarding coroutines; what is the difference between using: "yield WaitForSeconds(x)" and using "yield return new WaitForSeconds(x)". The [documentation][1] uses the first one, but I see the latter being used a lot on answers, forums, and amongst co-students. [1]: http://docs.unity3d.com/Documentation/ScriptReference/index.Coroutines_26_Yield.html