The Deores have pad holders, you can replace the pads with pretty well any pad insert you like, just by removing a little pin and sliding pads out and in. Like running Koolstop Salmons in the winter and normal pads in the summer. The Alivios have one piece pads, when you wear them out you have to replace the whole pad and re-set up the alignment.
But... you could equally buy the Alivios and install a set of cheap pad holders for less than the price difference, but you'd still need to pay for good inserts.
The Deores are good brakes though, very little flex in the arms under hard braking.