A certain theory of substance, one that grows out of Aristotelian philosophy but which has adherents today as well, draws a distinction between the features a substance has by instantiating a universal and the features it has by possessing a trope. An adherent of this theory might say that a certain cat is red because it possesses a redness-trope, but that it is a cat because it instantiates the universal CAT. A problem that must be faced by philosophers who hold this sort of view is the following: Which features are which? In other words, which features are the ones had in virtue of trope-possession, and which are the ones had in virtue of instantiation? In this paper I discuss this problem, consider and reject a competing view, and propose my own Aristotelian solution. I also raise and answer an objection.