What is the difference between the dairy products quark and skyr?
Stiftung Warentest, a famous German consumer protection agency, actually tried to answer that question and even had trained food testers try to determine the difference in taste. The result was basically that Skyr is very close to lightly beaten (Mager-)Quark, but with a higher acidity closer to traditional Yoghurt than traditional Quark and with a higher calcium content.