Audio and audio+?

I tried to backup an Audio CD in Alcohol, but what are different on audio and audio+. Safe disk ans safedisk2 i understand the different between.

Audio CD got a Key2Audio protection

Audio CD+ datatype will also read any sub-channel data that may be present in the original audio disc. If you want to backup karaoke CD’s you’ll have to use this datatype. Some audio protections may require this datatype too, but the most important thing in that case will be a CD/DVD reader capable to deal with the copy protection.