The fundamental difference between classical and quantum information theory, and by extension between the construed world of stuffs and the mystiweirdical underlying reality that somehow supports it is that in classicland a bit of information is atomic, indivisible and exhibits no interference behaviour, whereas quantopia has a very different basis: information can be indefinitely divided past the point of unity, and due to the presence of phase, the partial-informations can add (superpose) both constructively and destructively.
Otherwise put: the quantum world has halfstuffs, and the interaction of halfstuffs exhibits a more interesting and fruitful range of behaviours than the interaction of atomic and nonphased classical stuffs.
There is still a lot of investigation to be done on the application of this fundamental difference in bases to many of the things we classically do with stuffs.