Hmm from what I know that's exactly what they are, you study from friday to sunday. This allows people to work and study in the same time. In Poland they are usually easier ( they exclude lots of subjects from the full course ). Many times people who are not able to get into the normal course drop to "studia stacjonarne". Often degrees claimed during such courses are prized much less than the "full" counterpart.
The Polish Constitution says that education also higher education has to be free. That is why high schools in Poland invented a trick to make possible to charge students for their studies. They offer “normal studies” ( studia dzienne) for free and other studies they call them “zaoczne” oder “niestacjonarne”. The form of these studies is sometimes different but sometimes the same. The point is to charge students (-:
The best example is medicine. The only one real difference between “studia dzienne” and “niestacjonarne” is money (-: