I'll have to be carefull what i say here as i aint exactly sure if i'm correct...

But the way I understand it, the bluefin is like a general upgrade, it doesn't take into account any particular mods as such so it's the same 'tune' for every car... pretty much like an old superchip would have been for an RST, it pretty much just slightly upgrades everything...

Whereas the Dreamscience is or at least can be matched to you specific mods on your car, so is much more like a Live map which is why it give far better results?