Bob and Paul exemplify human nature. Bob and Paul are two different persons. The human nature Bob and Paul exemplify is such that human nature in Bob is distinguishable from human nature in Paul. Human nature is differentiated in Bob and Paul. This differentiation, however, is not the same as the exemplification. That Bob and Paul both exemplify human nature does not imply that human nature is differentiated in Bob and Paul, but is presupposed by it (of course). Differentiation, in other words, implies exemplification; the reverse is not true (considering differentiation and exemplification in themselves).