It is a bit the other way around. {$ifend} is a legacy notation that closes {$if}. Nowadays you can use {$endif} for both {$ifdef} and {$if}.
I still prefer to close {$if} with {$ifend} and close {$ifdef} with {$endif}.
But is is not required anymore. Reason is simply Delphi compatibility.
But the old way makes more notational sense.