I will have to check mine (standard screwdriver version) but I thought they were standard 1/4" bits?
If they are the same bits that are in the Zilla Jr then I don't think they conform to any standard sizing. As I understand it, after the success of the Zilla and Guppie they ordered more but at a 17% reduction, not realizing the factory would take it literally and reduce the standard bit size by 17% (or whatever the actual number was- for some reason I have 17% in my head for this) as well. This was why the Get A Way Driver actually exists- if you take the bit holder out of the front you'll notice that the end fits in the smaller Zilla Jr slot, so it works as an adaptor to use standard bits with the Zilla Jr.
As for it not being the right sizes to fit their own tools, well I can't comment on that as I don't have the Torx versions, but that does seem odd.
Def