What makes iTunes Plus different than the regular iTunes? The term iTunes Plus refers to an encoding standard on the iTunes Store where some songs and music videos are provided in high-quality AAC format and don't have Digital Rights Management (DRM). The two main differences between these standards are:Downloaded files aren't encrypted with Digital Rights Management protection.The bitrate or quality is twice that of the original iTunes standard.
Compatible With More Devices
Before Apple introduced iTunes Plus, iTunes customers were restricted on how they could use their purchased digital music. With the iTunes Plus format, you can burn your purchases to a CD or DVD and transfer songs to any device that supports the AAC format. This change also means that you aren't restricted to using Apple devices such as the iPhone, iPad and iPod Touch.
However, the newer standard isn't backward compatible: older-generation Apple devices cannot support the higher bitrate of the upgraded format.
Higher Quality Music
The iTunes Plus standard gives you the freedom to listen to your songs and music videos on a wider amount of hardware devices while also offering better quality audio for users. Before the introduction of iTunes Plus, standard songs downloaded from the iTunes Store were encoded with a bitrate of 128 Kbps. Now users can purchase songs that have twice the audio resolution: 256 Kbps. The audio format used is still AAC, but only the encoding level has changed.
Songs in the iTunes Plus format use the .M4a file extension.
If you have songs in the original format, you can upgrade these by subscribing to iTunes Match, but only if they are still in Apple's music library.