From the iTunes help file:
Quote:
To see where a file was purchased, select it, choose File > Get Info, and then look in the Kind field. Files purchased from the iTunes Store end in “.m4b.” Files purchased from the Audible website end in “.aa” or “.aax.”
To see who downloaded an Audible file, select it in the library and choose File > Get Info. The Purchased By or Owner field shows the user name for the account holder who downloaded the file.
|
Looks like the iTunes versions are a different format.