<?php

$fruit = array('banana','apple','tangerine','orange','lemon','lime','kiwi','mango','guava');
$citrus = array('orange','lemon','lime','tangerine');
$others = array_merge(array_diff($fruit, $citrus));
var_dump($others);


?>

array(5) {
  [0]=>
  string(6) "banana"
  [1]=>
  string(5) "apple"
  [2]=>
  string(4) "kiwi"
  [3]=>
  string(5) "mango"
  [4]=>
  string(5) "guava"
}