MP3 (MPEG Audio Layer 3)Â
a common format for consumer audio, as well as a standard of digital audio compression for the transfer and playback of music on most digital audio players.
M4A / AAC (MPEG4 Audio / Advanced Audio Coding)
an audio coding standard for lossy digital audio compression. Designed to be the successor of the MP3 format, AAC generally achieves better sound quality than MP3 at similar bit rate.