Megafiddle has the right idea. When PG Music makes the recordings that will become RealTracks, they record them as .WAV files, CD quality. These are the files you get with the audiophile edition.

To make the 'regular' edition, they compress these files to .WMA format, to about one-tenth the file size. With over 1000 RealTracks, this difference in size on the hard drive is considerable. Doing so means there is a loss of some audio quality. It isn't a great difference. If you want to have more discussion on that, we can talk more about it. Bottom line, if you intend to make commercial use of your backing tracks, then you would want the audiophile edition.

Then, probably more detail than you need to know at this point, but Megafiddle mentioned the concept, it is possible to uncompress the .WMA files. Although this is done automatically when you use the program, it does not change the quality. If you choose to batch uncompress the files (an option), it makes them much larger (back to the original size the .WAV files would have been) but it saves a tiny bit of time running each song since the program does not need to uncompress on the fly, so to speak.

But I'm guessing you are most interested in the second paragraph.

BIAB 2025 Win Audiophile. Software: Studio One 7 Pro, Swam horns, Acoustica-7, Notion 6, Song Master Pro, Win 11 Home. Hardware: Intel i9, 32 Gb; Roland Integra-7, Presonus 192 & Faderport 8, Royer 121, Adam Sub8 & Neumann 120 monitors.