从数组中删除存在于其他数组中的值

I am having two array. in PHP

dir(0=>1,1=>2,2=>3,3=>5,4=>7,5=>8);
list(0=>1,1=>12,2=>18,3=>20,4=>7,5=>8);

Resulting array should be

result(0=>2,1=>3,2=>5);

the result array should contain the values which is not exist in list() array

$diff=array_diff($dir,$lists);