M2TS (MPEG-2 Transport Stream) is a Blu-ray BDAV container format that uses MPEG-2 transport stream and comes with a .m2ts filename extension. It can manipulate audio, video, and other metadata such as disc menu and subtitles. At a bare minimum, any Blu-ray player should play M2TS files easily.
MP3 is a standard audio format developed by Moving Picture Experts Group and uses MPEG-1 and MPEG-2 standardizations. MP3 uses lossy data compression, meaning that it loses quality over time. This sound format comes with a .mp3 filename extension and is today the most common audio format on websites and multimedia players.
Windows Media Player iTunes, Mplayer VLC Media Player