<?php
$date1=mktime(0, 0, 0, 7  , 22, 2013);
$date2=mktime(0, 0, 0, 7  , 23, 2013);

echo $date1."\n";
echo $date2."\n";

if($date1>$date2)
{
	echo "Date1 is greater";
}
else
{
	echo "Date2 is greater";
}
?>

1374451200
1374537600
Date2 is greater