The touring seat has a far larger & cushier passenger (and rider) seating area. It's not the most terribly attractive seat, but effective.
The passenger pillion from Corbin is also slightly larger and better contoured. So far I've resisted the urge to spend $700 on a rider seat, passenger pillion and backrest.
I put a Saddleman gel-pad under my factory seat, so far with good results. There are pix in my photo gallery. I'll probably do the same to the wife's pillion. It won't make it any larger, just a little more comfortable for a reasonable cost.