They are both HUGE, with the auto being very slightly bigger than the eco versions. Also the Auto has the large valve sticking out of the side, which the eco lacks. Construction is similar but different in both watches and in my experience the bezels on both are a little awkward to grasp and turn. they are definitely not sooth like seiko bezels, but more of the ratcheting type. Personally I have 7.5" wrists and I find both too big for me.
Strange as ive always wanted the Autozilla yet ive managed to aquire the zilla st/steel and the Ti Zilla.Both are perfect for me as i like my watches huge.Ive yet to hold or compare the 1000m version but i would love to own one.
Plus theres always this to keep me happy Size wise.
Not a Zilla but should be!!Its a Monster all the same.