The big difference is that the head on the 7880 has a teflon coating. The advantage to this is that there is far less clogging with PK ink on the 7880 machine than on the 7800. The new magenta ink formulation for the 7880 results in a modestly expanded gamut that, as far as printing photos is concerned, isn't relevant 99.999% of the time. The expanded gamut may help you hit a few more PMS reds and pinks.
