As the name suggests, audiobooks are voice recordings of the text of a book that you listen to rather than read. Audiobooks can be exact word-for-word versions of books (unabridged) or abridged versions.
The difference between abridged and un-abridged is the length of the book. An abridged audiobook is a shortened version of the book. You'll get the main idea of the book just not all the smaller details. An unabridged audiobook contains all the original content of the book and will be read by a narrator (usually specified in the product description or cover art).
In the case of Chuck Missler's Commentary and some Topical studies, the audiobooks are not narrated, but are the same content as the MP3/Audio Download versions. If you alread have the MP3 or Audio Download versions of these products, you do not need the audiobook version.
Our Audiobooks come in MP3 format as either MP3 CD-ROM or Download.