array_variation.php

<?php

function array_variation($old, $new) {
  $new_map = array_flip(array_values($new));
  $old_map = array_flip(array_values($old));

  return [
    "added" => array_filter($new, function($e) use ($old_map) {
      return !isset($old_map[$e]);
    }),
    "removed" => array_filter($old, function($e) use ($new_map) {
      return !isset($new_map[$e]);
    }),
  ];
}