As MSDN says:
Closed event is deprecated in the .NET Framework version 2.0; use the FormClosed event instead.
I do not think you should even use this event. It is outdated and hidden, but it is there only for compatibility with the old source code.
It has the same meaning for the FormClosed event, but with one (not so much) subtle difference, as you can see on MSDN. The Closed event does not occur when the application exists, because the call to Application.Exit() but FormClosed is.
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