Focus is specifically put on some of the main conceptual and methodological differences between these two approaches, while demonstrating the advantages and value of each through notable examples in the recent literature. Finally, we comment upon insights realized, remaining challenges, as well as the prospects of combining the two "schools of thought" in future research. A phenomenological treatment of the surface kinetics, e.g. via a Butler-Volmer expression, generates an empirical J surf that is (usually) combined with modeling more complex transport phenomena and design strategies at the device level. On the other hand, a first-principles based microkinetic model (1p-mkm) integrates into J surf a predictive-quality description of the free energy reaction path with specific focus on elucidating the underlying microscopic catalytic mechanism.