excellent pictures and i can see that you're quite right, our VM nib units do appear to be the same after all. and a lot more similar to the OP's than i originally understood to be the case. it had never occurred to me that the inner nib unit screwed into the sleeve which in turn screwed into the pen body. the OP's picture had me thinking it was constructed differently: i'd imagined that the sleeve on the nib section of the OP's VM was part of the pen body and the nib unit fit through that to screw into the pen body itself, not threads within the sleeve. clearly it's just a matter of the OP having partially disassembled his from the get-go rather than having unscrewed the whole nib assembly and then disassembled that, as you did in your most recent pictures.
well, there we go! mystery solved and my mistake all along after all. my apologies for doubting your previous observations.
that said i'd still say the recent VM looks a whole lot more like the Diamond Mini in the OP's picture than it does the his VM but it would seem that's more perception than fact.
(heads off to correct other posts)