Unnamed vs. Named prepared statements in PDO

gistfile1.php

//UNNAMED
$query = "SELECT userid FROM t1 WHERE (username = ? OR useremail = ?)
   AND usertoken = ?";
$prepared_statement = $db_connection->prepare($query);
$prepared_statement->execute(array($_POST['login'], $_POST['login'],
   $_POST['token'])
);
 
//NAMED
$query = "SELECT userid FROM t1 WHERE (username = :login
   OR useremail = :login) AND usertoken = :token";
$prepared_statement = $db_connection->prepare($query);
$prepared_statement->execute(array('login' => $_POST['login'],
   'token' => $_POST['token'])
);