- var_dump: documentation ( source)
- array_diff: documentation ( source)
<?php
$anArray = array(array('black'), array('p'));
$anotherArray = array(array('white'));
var_dump(array_diff($anArray , $anotherArray));
//var_dump((is_array($anArray) && is_array($anotherArray) && array_diff($anArray $anotherArray) == array_diff($anotherArray, $anArray)));