Audi Navigation Dvd Audi Navigation?

Audi navigation? - audi navigation dvd

I found just a RNS-D to 585th on eBay I would get a RNS-E, but I do not want a big stomch for radio at this point. My question is, as I see, said the RNS-D, a CD of maps based on the RNS-E is on DVD. What is the difference? I also see a few places to say that the RNS-D not playing music CDs. Can someone light on this? The navigation is for Audi A4 B6 (2002-2004), I fit an A6 2002nd Thanks for all the answers to the question, which I appreciate.