C#: What is the difference between async Task and async void?

1// async Task — OK
2public async Task DoWork() {
3    await Task.Delay(1000);
4}
5
6await DoWork();  // Can await
7
8// async void — dangerous
9public async void DoWork() {
10    await Task.Delay(1000);
11}
12
13// DoWork();  // Cannot await