just from a technical perspective.. DVD format on a player means the unit can read DVD discs in addition to regular CD discs... DVDs offer alot more space for storing data...(in this case music files) MP3s can be written to blank CDs but you can also burn them onto a blank DVD disk too..(and you'll fit 100 times more music)

at the end of the day the unit will still play the contents of both discs...(just alot more music if it's coming from a DVD disk)

as for sound/music quality....it all depends on the recorded format, MP3 or other format you copy it to, and that format must be supported on the sound system unit itself...

I believe the X5 system supports only CDA and MP3 formats only.

DVDs also support music videos....but I don't think you'll be able to view them on the iDrive dash screen...

you can on the rear entertainment system...

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2012 X5 50i M-Sport
2014 X3 35i M-Sport