Abstract. We present a side by side comparison of Capsules and Closures, including a proof of bisimilarity, using small-step semantics. A similar proof was presented in [8], using big-step semantics. However, while big-step semantics only allow to talk about final results of terminating computations, the use of small-step semantics allows to prove a stronger bisimilarity involving every step of the computation and thus also applicable to infinite computations.