type
   TMyClass=class
      x: array of integer;
      constructor Create;
      destructor Destroy;
      destructor Free;
   end;

constructor TMyClass.Create;
begin
   setlength(x, 10);
   x[7] := 19;
end;

destructor TMyClass.Destroy;
begin
   ShowMessage('6');
   setlength(self.x, 0);
end;

destructor TMyClass.Free;
begin
   ShowMessage('5');
   setlength(self.x, 0);
end;

procedure TForm1.Button1Click(Sender: TObject);
var
   c: TMyClass;
begin
   c := TMyClass.Create;
   try
   finally
      c.Free;
   end;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
   c: TMyClass;
begin
   c := TMyClass.Create;
   try
   finally
      FreeAndNil(c);
   end;
end;

TMyClass=class
   x: array of integer;
   constructor Create;
   destructor Destroy; override;
end;