使用括号与不在地址上使用括号有什么区别

Version without parentheses:

Route::get('/read', function(){
    $user = User::findOrFail(1);
    echo $user->address->name;  // <- this line
});

Version with parentheses:

Route::get('/delete', function(){
    $user = User::findOrFail(1);
    $user->address()->delete();
});

The difference is that the first one:

$user->address->name;

returns an eloquent instance so you can get the properties out of it, and the second:

$user->address()->delete();

returns a Query Builder instance on which you can perform SQL queries as you already do, so it will delete the row from the database.