StringsInPHP - //Problem 1. Removes Names

//Problem 1.    Removes Names
//Write a script that takes as input two lists of names and removes from the first array all names given in the second array. The input //and output array are given as words, separated by a space, each list at a separate line. Examples:
<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8">
        <title></title>
    </head>
    <body>
        <form method="post" action="RemoveNames.php">
            <input type="text" name="str1">
            <input type="text" name="str2">
            <input type="submit" value="GO">
        </form>
    </body>
</html>

<?php
$string1=$_POST['str1'];
$string2=$_POST['str2'];
$arr1 = explode(" ", $string1);
$arr2 = explode(" ", $string2);
$difference = array_diff($arr1, $arr2);

foreach($difference as $v){
    echo $v.'&nbsp';
}


?>