Diff between two time location by timezone & date

<?php

date_default_timezone_set('Asia/Tehran');
$aaa1= time();
date_default_timezone_set('Europe/Paris');
$aaa = date("Y-m-d H:i:s");
date_default_timezone_set('Asia/Tehran');
$aaa = strtotime($aaa);
$Final = $aaa1 - $aaa;
echo $Final;
exit(); 

?>