This article is from the The Osbourne FAQ, by Mike L. with numerous contributions by others.
Ozzy's music company has time and time again released his music under
different titles, with different artwork and with different music
selections. If you own Ozzy's entire collection of music, is there
really any point in buying another CD of the same songs you already
own just to have that CD with different artwork?
If you own all of Ozzy's albums, do you really also need The Ozzman
Cometh, Ten Commandments, Bible of Ozz, Best of Ozz and The Essential
Ozzy Osbourne? Apparently so, not to mention the half a dozen live
albums as well.
It's marketing baby, and that's what his record company is paid to do.