Could some one explain the difference ?

Which Program is good for let's say a Itunes comparison?

ogg and mp3 is the media format in which music/sound files are encoded...
you can google for it for more information regarding file formats.

If you want a same interface as itunes, you can try rythmbox.. sorry if i spelled it wrong... it supports i-pod connectivity too (may be not the new ones) but i shud say give a try to amarok too... its an elegant player. for playing mp3 on any of the players, you need to install gstreamer codecs. chk out my weblog for more info regarding codecs installation for amarok. http://casquid.wordpress.com/

ogg and mp3 are both audio formats with lossy compression (that is they lose some of the original quality to greatly improve the compression ratio)

ogg is easily supported in Linux and almost every freshly-installed Linux distribution can play ogg files.

But the mp3 algorithm is patented, not allowing programmers to give away the source code for others to see, and this is against what many Linux distributions allow, so mp3 under Linux is a bit of a pain, but you can still play them if you install certain (non-FOSS) packages.

The ogg format (or more accurately the vorbis codec, ogg is just the container format) is generally considered slightly superior to mp3 in quality. That is, you can get slightly better to-the-ear sound for the same file size, or conversely the same quality sound in a smaller file. On the other hand, ogg doesn't have the same level of overall support that mp3 does; in particular most portable music players cannot handle ogg. Most of the better software players have support though (but don't expect Windows Media Player to recognize it!).

And as already mentioned, IP issues affect mp3, meaning that most FREE distributions cannot include the codec by default. It is legal for individual users to install mp3 software on their own systems though, and codecs are available gratis.

The ogg container and vorbis codecs, OTOH, were created specifically to provide for a truly FREE alternative to IP-encumbered multimedia formats. There are no known issues involving patents or other IP (although you never know when it comes to software patents), and the code is all open source. Anyone can distribute them.

So what this boils down to is, if you want superior quality and freedom, use ogg vorbis, if you need portability and don't mind the restrictions (admittedly non-burdensome at an individual level), then mp3 will do. But you'll probably have to install it yourself.

I actually took the listening test on ogg Vorbis's website, and compared to an mp3 sample of the same file size the ogg quality was really amazing!

Some ogg files are actually videos using the non-patented Theora codec.

http://www.xiph.org/vorbis/listen.html

thanks !