Ciacona, e moll (BuxWV 160)

I've always had difficulty to define the difference between a ciacona and a passacaglia. A difference could be that in a Ciacona the bass melody stays in the bass voice, whereas in a Passacaglia, the variations include the melody being played in the other voices as well.

I don't know whether this is true for all Ciaconas and Passacaglias in existence. It is (mostly) true however for the Ciacona's I am familiar with.

This beautiful Ciacona is no exceptiom. The melody, or harmonic outline, and the variations thereof are restricted to the lowest sounding voice. It sounds 31 times in various variations. Can you spot them all|?