Exist removed and added new array in PHP

$exist  = [1,2,3];
$update = [1,2,4,5,6];

//Action
//1 - Remove no 3
//Add 4,5 and 6

//Both exist before and after
//1,2

$both_exist = array_intersect($exist,$update);


echo ('Check removed');
$removed = array_diff($exist,$both_exist);
echo '
';
print_r($removed);
echo '
';

echo ('Added');
$combined = array_unique(array_merge($exist,$update));
$added    = array_diff($combined,$exist);
echo '
';
print_r($added);
echo '
';