I don't know technical details, but an Audio CD is slightly different from a data CD even if contains only WAV files.
If you insert an audio CD on a computer drive, it will not show the actual WAV files, but a list of short (1 Kb) files with .cda extension. If you insert a data cd into the drive, all WAV files will be shown.
I must say that I never tried to insert a data CD containing WAV files into a CD player, so I have no idea if the player will be really able to read it.
So, to be sure to get the best compatibility (mostly with older players), I suggested to not use a data CD
Another thing I forgot to mention, is that older players are really picky with burned discs, so I suggest to burn these CDs at the lowest speed possible (not more than 16x anyway). If you burn discs at a too high speed, it is possible that you'll get a too high jitter, and the player can be not able to recognize the disc at all :doh: