Three friends have been arguing this out, to no firm conclusion. The strongest argument against is that a cinnamon roll is (usually) baked and a donut is (usually) fried. But there are exceptions, as well as crossover versions 1]2]3]. To complicate, cinnamon rolls can be made from donut dough. Can they be the same, or not (either logically, or using empirical evidence)? Assume donut (US) = doughnut (UK).