<?php
$array1 = array(
    "http://content-available-to-author-only.com/photo-30666517_315641240",
    "http://content-available-to-author-only.com/photo-63314435_318050082"
);
$array2 = array(
    "photo-30666517_315641240",
    "photo-163314435_318050082"
);
$out=array();
 foreach($array2 as $val) {
    foreach($array1 as $value) {
        if(strpos($value, $val)) {
           continue 2;
        }
    }
        $out[]=$value;
 }
 print_r($out);
 

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