I heard the term "owned apartment" once and it is precisely what we call here a "condo". It was actually a condo conversion (a place that used to be for rentals and it was converted and sold as condo units).
There is no difference. A "condo" typically refers to an owned unit in a condominium development, whereas an "apartment" typically refers to a rental unit. The key is in knowing if the unit is for sale or for rent.