Add a method to determine if an orders changed date has been updated in the database

commerce_order.module

/**
 * Compares the given order's changed date against the database value.
 *
 * @param $order object
 *   A fully loaded order object.
 *
 * @return bool
 *   Boolean indicating whether or not the order object has changed.
 */
function commerce_order_has_changed($order) {
  $query = new EntityFieldQuery();
  $query
    ->entityCondition('entity_type', 'commerce_order', '=')
    ->propertyCondition('order_id', $order->order_id, '=')
    ->propertyCondition('changed', $order->changed, '>');
  $result = $query->execute();

  return (!empty($result)) ? TRUE : FALSE;
}