<?php

function tmCompare($a, $b)
	{
		return strtotime($a->tm) - strtotime($b->tm);
	}
	function ptmCompare($a, $b)
	{
		return strtotime($a->playertm) - strtotime($b->playertm);
	}

	date_default_timezone_set('America/Los_Angeles'); // For writecodeonline.com

	$data1 = '[{"matchID":"1","tm":"2014-01-16 08:55:13","playertm":"2014-01-16 08:55:14"}, {"matchID":"2","tm":"2014-01-16 09:53:50","playertm":"2014-01-16 09:53:52"}, {"matchID":"3","tm":"2014-01-16 09:58:49","playertm":"2014-01-16 09:58:57"},{"matchID":"4","tm":"2014-01-17 08:44:34","playertm":"2014-01-17 08:44:35"}]';

	$data2 = '[{"matchID":"3","tm":"2014-01-16 09:58:49","playertm":"2014-01-16 09:58:57"},{"matchID":"4","tm":"2014-01-17 08:44:34","playertm":"2014-01-17 08:44:38"},{"matchID":"5","tm":"2014-01-19 08:44:34","playertm":"2014-01-19 08:44:38"}]';

	$j1 = json_decode($data1);
	$j2 = json_decode($data2);

	$array1 = Array();
	$array2 = Array();

	foreach ($j1 as $single){
		$array1[$single->matchID] = $single;
	}
	foreach ($j2 as $single){
		$array2[$single->matchID] = $single;
	}

	$df1 = array_udiff($array1, $array2, 'tmCompare');
	$df2 = array_udiff($array2, $array1, 'tmCompare');

	$df3 = array_udiff($array1, $array2, 'ptmCompare');
	$df4 = array_udiff($array2, $array1, 'ptmCompare');

	print_r($df1);
	print_r($df2);
	print_r($df3);
	print_r($df4);

?>