I know there is a difference, my backup is a AFD first version as well, and I know it doesn't accept some of the newer lenses, notably the LS lenses, (there might be an upgrade for this, I don't know), and I don't believe it accepts the V-grip air. But functionality wise, the newer ones may have some more updated metering or autofocus system type things, but I do not believe there is any compelling difference between the models. I could be wrong though.