Alchol 120% VS Disc Juggler?

For some reason my Dreamcast will play some games when burned using 120% but some need Juggler (Yes I had to waste CDs :( )
What exactly is the difference?

DiscJuggler's .CDI format is the standard used for Dreamcast releases like we do at www.DCEvolution.net. - Alcohol120 should be perfectly capable of burning DJ images too.

And, you can use BootDreams for plain files.