iTunes Plus refers to songs and some music videos* in high-quality AAC format that don't have Digital Rights Management (DRM).
All songs now for sale in the iTunes Store are iTunes Plus. If you previously bought music with DRM from the iTunes Store, you might be able to download DRM-free versions of your songs with an iTunes Match subscription.
You can sync Apple music to your iPhone, iPad, or iPod touch or stream them to your Apple TV. However, if you want to transfer iTunes music to Samsung S4, you may failed. Now you should use a tool which can help you.
Macsome iTunes Music Converter (http://macdownload.informer.com/itunes-converter/)can help you. With it, you can convert apple music to plain MP3 or AAC audio. In this way, you can move the converted iTunes music to your Galaxy S4 at ease.