--Those cells really can't be differentiated from "adult stem cells". --
They can easily be differientiated from "adult stem cells" as these were differentiated and adult stem cells are NOT differentiated.
There's a continuum of development in stemcells, and various terms have been invented to more or less indicate the level of development.
Might be better to use those terms than to mess around with "differentiate" ~ particularly since that term has a quite ordinary meaning related to how I or you might see different things.