Stem cell question

From here we get

The team of researchers from Keio University School of Medicine in Japan extracted stem cells from a 14 day-old rat fetus. The type of stem cells they extracted are called neural progenitor cells, which are genetically programmed to later develop into various kinds of nervous system cells.

I thought the point of getting stem cells from a fetus was that any such stem cell could form any other type of cell, ie, it wouldn't matter what kind of stem cell you got from a fetus. Otherwise you could use non-fetal stem cells instead, which were more specialized and highly developed at the cost of the flexibility.