What is the difference between the Kurs C and Kurs D tests?

The tests have the same four parts. In Kurs D the texts are more formal. Reading (Läsa) has about 38–41 questions and listening (Höra) about 21–24. In writing (Skriva) you write two texts in Kurs D, and one of them is more formal. In Kurs C you write one text.