These are all audio formats in which you can covert a music file into by using tools such as iTunes. AAC format audio -I could not really hear a difference from this and the original or the AIFF.Quality was great and took up less space then AIFF. Mp3 high quality - Vocals where very clear and over all quality was closer to original sound on the CD. Mp3 good quality -i thought this quality was really poor, bass did not really bump also vocals seemed to be mashed with beat.( everything felt squeezed together) AIFF format -quality seems the same as AAC only difference is that it did sound a little grainy.