The array_diff() function compares ar1 against one or more other arrays and returns the values in ar2 that are not present in any of the other arrays.
Example
<?php
$array1 = array("lang" => "php", "java", ".net", "python");
$array2 = array("lang" => "perl", "java", "python");
$result = array_diff($array1, $array2);
print_r($result);
?>
