I have a question about ADS/CFT Correspondence. There is a quote from Wikipedia that confuses me. "Every entity in one theory has a counterpart in the other theory. For example, a single particle in the gravitational theory might correspond to some collection of particles in the boundary theory." How can two theories that describe the same thing sound so different? For example, one theory may have one particle and the other would have multiple particles. Why wouldn't they have the same amount? Why don't these two theories that describe the same thing sound more similar? Also, shouldn't only one of the theories be the correct one?