Abstract Factory with builder

Hello, i have a design patterns test, in that test i have to do abstract factory with builder in one program, i am confused because builder and abstract factory are so similar, we can choose bettwen them but i can't see where we can combine them
can someone tell me if i did anything wrong here in this code?

<?php

interface YoutubeFactory{
public function createVideoLibrary();
public function createMuiscLibrary();
}

class YoutubeFactoryForAdults implements YoutubeFactory {
public function createVideoLibrary(){
return new AdultVideoLibrary();
}
public function createMuiscLibrary(){
return new AdultMusicLibrary();
}
}

class YoutubeFactoryForChildren implements YoutubeFactory {
public function createVideoLibrary(){
return new ChiledVideoLibrary();
}
public function createMuiscLibrary(){
return new ChiledMusicLibrary();
}
}
interface ILibrary {
public function render();
}
class AdultVideoLibrary implements ILibrary {
public $link;
public $author;
public function render(){
return 'render adult video';
}
}
class AdultMusicLibrary implements ILibrary {
public $link;
public $author;

public function render(){
    return 'render adult music';
}

}

class ChiledVideoLibrary implements ILibrary {
public $link;
public $author;

public function render(){
    return 'render chiled video';
}

}
class ChiledMusicLibrary implements ILibrary {
public $link;
public $author;

public function render(){
    return 'render chiled music';
}

}

//
class YouTubeFactoryBuilder{
    public $factory;

    public function __construct($visitorAge){
        if($visitorAge>=18){
            $this->factory= new YoutubeFactoryForAdults();   
        }else{
            $this->factory= new YoutubeFactoryForChildren();   
        }
    }

    public function createNewFactory($factory_object){
         $this->factory = $factory_object;

    }

    public function getFactory(){
        return $this->factory;
    }
}

///client code

$bulder = new YouTubeFactoryBuilder(rand(0,100));
$factory= $bulder->getFactory();
$videoLibrary = $factory->createVideoLibrary();
$musicLibrary = $factory->createMuiscLibrary();

 echo $videoLibrary->render()."\n";
 echo $musicLibrary->render();