International audienceWe compare parametrized automata, a class of automata recently introduced by the authors, against finite memory automata with non-deterministic assignment, an existing class of automata used to model services. We prove that both classes have the same expressive power, while parametrized automata can be exponentially succinct in some cases. We then prove that deciding simulation preorder for parametrized automata is EXPTIME-complete, extending an earlier result showing it in EXPTIME