How does C# 5.0's async-await feature differ from the TPL?

Question

I don\'t see the different between C#\'s (and VB\'s) new async features, and .NET 4.0\'s Task Parallel Library. Take, for example, Eric Lippert\'s code from here:

Answer 1

The problem here is that the signature of ArchiveDocuments is misleading. It has an explicit return of void but really the return is Task. To me void implies synchronous as there is no way to "wait" for it to finish. Consider the alternate signature of the function.

async Task ArchiveDocuments(List urls) { 
  ...
}

To me when it's written this way the difference is much more obvious. The ArchiveDocuments function is not one that completes synchronously but will finish later.