<?php

$time1 = time2stamp('1431-09-01 10-30-00');
$time2 = time2stamp('1431-11-01 11-30-00');

$diff= stamp2time($time2-$time1);
print_r($diff);

//convert date to timestamp
function time2stamp($date){
    list($date, $time) = explode(' ',$date);
    list($y,$m,$d) = explode('-', $date);
    list($h,$i,$s) = explode(':', $time);
    return(($y*31557600)+($m*2592000)+($d*86400)+($h*3600)+($i*60)+$s);
}

//convert timestamp to date 
function stamp2time($sec){
    $time['y'] = floor($sec/31557600);
    $time['m'] = floor(($sec%31557600)/2592000);
    $time['d'] = floor(($sec%31557600%2592000)/86400);
    $time['h'] = floor(($sec%31557600%2592000%86400)/86400);
    $time['i'] = floor(($sec%31557600%2592000%86400)/3600);
    $time['s'] = floor(($sec%31557600%2592000%86400%3600));
    return($time);
}

?>