array array_diff ( array arr1, array arr2 [, array ...] )
$toppings1 = array("Pepperoni", "Cheese", "Anchovies", "Tomatoes");
$toppings2 = array("Ham", "Cheese", "Peppers");
$diff_toppings = array_diff($toppings1, $toppings2);
var_dump($diff_toppings);
?>