We compare the expressive power of two automata-based finite-state models of concurrency. We show that Droste’s and Kuske’s coherent stably concurrent automata and Bednarczyk’s forward-stable asynchronous systems describe the same class of regular event structures. This connection subsumes a previous study by Schmitt which relates Stark’s trace automata to asynchronous systems. This work relies on Zielonka’s theorem and some unrecognized result due to Arnold.