The 905's lens (indeed redesigned) has the CFi barrel (which gives smoother focussing, different grip surfaces, different typeface, better grip of flash cable, longer lasting shutter main spring inside).
Early 903 SWCs, up to 1995, have the first style tripod quick mount plate underneath, later 903 models and the 905 has the present style plate.
And that's it.
Oh, and the 905 SWC comes with a lens hood, which you had to buy separately before.