What is the difference?

What do you mean? You've been a member for quite a while and with all those post I would assume you would have an idea:
You have a CCC cause you have NAV and you are in the states (All cars with NAV in the US have Prof. NAV which requires a CCC). All cars w/o Prof. NAV don't have a CCC but a M-Ask unit. In summary, up to what I know, there are three different kinds of M-Ask: The Business radio, the proffesional radio and the business NAV (This last one is not available in the US)

The CCC has two CD slots (One is regular CD and the other is DVD), the M-ask unit only has one slot

In the US the first E60s (I think up to Prod. date 03/2005) came out with M-Ask business radio unit and don't play MP3.
Not sure if I'm addressing your question at all since it is kind of vague. Plenty of info in this forum regarding M-Ask and CCC

Thanks for the info. I had no idea about the two. Just beacuse I have alot of posts, it doesnt mean I know everything, thats why I am still a member. I never had to look into any of the two, since my car always played MP3, but this post got me thinking:

http://forums.e60.net/index.php?showtopic=36144&st=0#