What is the difference between mp3 and mp4 and vcd and dvd

Both are a matter of formatting. Kind of like .doc vs. . txt. The only significant thing to know is whether your device will play (or open) the formatted file.

I'm more familiar with vcd vs. dvd than I am mp3 vs. mp4:

Vcd stands for Video CD. It's a format that used to be mostly for karaoke, but is now used sometimes with other video material.

Nowadays most dvd players also play vcd.

Here is a good link explaining the differnces between VCD, XVCD, SVCD, XSVCD and DVD formats:

http://www.videohelp.com/

MP3 is an audio compression format. MP4 is video, similar to MP1 (ued for VCD, XVCD) and MP2 (used for SVCD, XSVCD, DVD).

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