mp3/mp4

[Mawby]

Can somebody please explain how an MP 4 works different from an MP 3

[ChuckFickens]

They work in pretty much the same way, except that mp3 is compressed audio, mp4 is compressed video and audio. (though you can get MPEG-4 audio only files, but these would normally have a m4a file extension)

[Gromit]

I believe Mp4 files have greater compression for the same quality, so you can fit more of them on a player.

[Mawby]

Thank you Chuck and Gromit, that probably explains why one is more expensive that the other, Mawby