Richard has written a fantastic post about how design (read graphic design) and advertising is separated by a common language. Having been working on a project with our design department on a pure design project recently, I think there's also something very different (and refreshing) about how they tend to like to work compared to the usual advertising creative. (I sense I'm opening up for myself with abuse with these sweeping generalizations as I know the best creatives I've worked this also have a tendency to work this way, and it's the way the best work tends to get done.). Here goes:
They make stuff. Stuff that shows the working out. They do stuff and then learn from it. You end up with tangible stuff on a wall to react to and have conversations about.
I for one intend to learn from this and work like this more often - less abstract talking and theory and more concrete doing.