Compressible two-phase flows have a wide range of applications. There are numerous models available in the literature. Typically these belong to the class of diffusive-interface (DI) models or sharp-interface (SI) models. Although there is a rich literature available on the modeling and the simulation of two-phase flow, there is much less work spend on the comparison of different models. The objective of the presentation is two compare a DI model with an SI model for isothermal two-phase fluids. For an SI model we consider an isothermal Euler model. Here the phases are separated by a sharp interface. Thus, the fluids interact only at the phase interface where the exchange of mass and energy across the phase interface has to be modeled appropriately by kinetic relations. For a DI model we consider an isothermal Baer-Nunziato-type. Opposite to the SI model, in the Baer-Nunziato (BN) model it is essential that all components of the mixture are present in each point. Thus, to compare the BN model with the SI model, it will be essential that (i) the asymptotic limit for vanishing volume fraction of the BN model coincides with the Euler model of the pure phases and (ii) the relaxation processes in the BN model describe the exchange of mass and energy across the phase interface of the SI model in the asymptotic limit. For this purpose, we perform a Chapman-Enskog-type expansion. The asymptotic analysis is complemented by numerical simulations. For this purpose, we perform computations for the configuration of a vapor-vapor expansion problem near pressure saturation with and without mass transfer. The results are compared to the SI model.