But that sounds like a difference between two models, not a difference between two physical objects. To me it seems that if you were to follow this line of thin

But that sounds like a difference between two models, not a difference between two physical objects. To me it seems that if you were to follow this line of thinking religiously, you could then never say things like "an atom of carbon has six protons", since, well, they're not quite protons according to this logic.