Zippy did a quite good write-up
Well, the things I know are the 777H does have a black tuning scale while the Z one has a blie scale and they also have different radio bands but that is nothing new.
The 777E probably was sold in the UK only...maybe only came with a different power cable!
The 767Z and the 767H only are different in the radio bands and follow the same color scheme.
The 909 is a slightly less feature-filled version of the GF999. It was probably cheaper so people could afford it. Otherwise they do have the same design if you take away the bigger VU cut-outs and details like that.
Then the 919 is summed up quickly. It is a GF777 with Japanese writing on it for the domestic Japan market.
The 999 has many more features than the 777 (like tape pitch, etc.) but still less features than the GF1000. I think when you had to decide between the GF999 and the GF1000, it was all about the looks your prefered.
Then the GF1000 features a longer band of APLD, tape pitch control, various mixing functions and so on. Just like the 999 it has 4 inputs below the speakers which I could never quite identify. The protection bars on the outer speakers are missing and they also have chrome dust caps. Different tape doors as Zippy said and GF767 styled knobs.
That's about what I can add here.
