Advanced Settings in DiscJuggler 3, plz Help

[Fressor]

Hi...

I just leeched some gigs of games, because i ordered a dreamcast which should arrive tomorrow or so.
Because i'm new to this, i wonder if there's any difference between "mode1" or "mode2" setting in the advanced tab in DiscJuggler.
At a friend of mine we burnt a game with mode1 and it worked (Sonic2). But in many tutorials i read that one has to set "mode2" to get it to work properly.

Additionally, everyone tells that you don't have to change any settings in discjuggler. but we left the original setting (audio) and got a coaster with sonic2. it worked when we set it to mode1...

but should it be mode2 ?

really confused...
fressor
thx for your answers