To say that two things are really distinct simply means that one thing is not the other. Thus a chair and a desk are really distinct simply because the chair is not the desk.
This argues against the formal distinction of Duns Scotus, because if we take two things which are said to be formally distinct in his sense, either the first is not the second, or the first is the second. If the first is not the second, they are really distinct, and there is no need for his formal distinction. If the first is the second, then they are really the same, and it is enough to speak of a distinction in concept.
However, it should be noted that in another sense, no distinction is real. The distinction consists in the fact that one thing is not another, and “not being another” is not a being, but a lack of being. Thus distinction is always something generated by the mind when understanding reality, rather than something that exists in itself.
Nonetheless, “this concept differs from that one” differs from “this is not that,” and consequently we distinguish between conceptual distinctions and real distinctions in this way, even though in themselves all distinctions are conceptual.