"What is the difference?"
Translation:Was ist der Unterschied?
I'm not sure but I would almost call it a "false friend".
The difference = der Unterschied Die Differenz = difference [MATH.!!] the margin (?)
When I hear "Differenz" it is for me a mathematical thing. But also people can have "Differenzen" means disagreements. Because I'm just a German not a teacher let me give you some examples.
Die Differenz von 5 - 2 ist 3. Peter und Jack haben Differenzen. Sie streiten sich über ... Was ist der Unterschied zwischen Käse und Käsekuchen?
In the last sentence you would never use "Differenz" but always "Unterschied". You ask what two or more things have not in common and the answer is "der Unterschied".
I hope that helps.
I'm glad to hear that. I think german is a pretty difficult language. And every time I'm reading here in the forum or speak with foreigners/non-locals I think, is my language really that weird and I have to admit, yes it is. So for you and everybody who learns german (Why ever): Hats off! Respect!!
best regards Angel