As Roy-Vidar says, the Unload event can be cancelled, the Close event can't.
So if you want to prevent the form from closing under certain circumstances,
the Unload event is the place to do that. If, on the other hand, you have
some code you want to only run if the form has definitely been closed, and
you do not want that code to run if the closing of the form is cancelled,
then the Close event might be a better choice. You could do it by using an
If ... Then ... Else ... End If in the Unload event, and placing the code
that should run only if the form is definitely going to be closed after the
'Else', but dividing the code between the two events is, in my opinion,
cleaner and more elegant.