CASTs seem to be of both types. They are, after all, based on the old Phantasy Star mechanical companions, and if you remember, Wren in PhS4 was entirely mechanical, while Demi was partly organic. Similarly, in Phantasy Star 3, Mieu was partly organic, while Wren was entirely mechanical.
It's two different Wren, by the way. The one in PS3 was SHIREN in the original, while PhS4's was FORREN.
Not exactly, Rohr. An android could be a robot or synthetic organism, meaning a living thing with biological functions that is built, not born. It's an amorphous term compared to "robot" and "cyborg."
That, and there's a lot of hints in PSU that CASTs/CASEALs are more human than they let on. I saw a synthesis board for a food item that mentioned the food was "popular among CASTs," and it turned out to be a vitamin pill.
A robot wouldn't need vitamins; once you get robots that eat for energy or the like, you're getting into synthetic organisms.