laravel order by desc

1$posts = Post::orderBy('id', 'DESC')->get();

1->orderBy('id', 'DESC');

1$orders = DB::table('orders')
2                ->orderByRaw('updated_at - created_at DESC')
3                ->get();

1/**
2 * Show the application dashboard.
3 *
4 * @return \Illuminate\Http\Response
5 */
6public function index()
7{
8    $messages = Message::select("*")
9                            ->where('receiver_id',$id)
10                            ->orderBy('created_at', 'desc')
11                            ->get();
12  
13    dd($messages);
14}