Jonsson and Larsen's notion of probabilistic simulation is studied from a coalgebraic perspective. The notion is compared with two generic coalgebraic definitions of simulation: Hughes and Jacobs' one, and the one introduced previously by the author. We show that the first almost coincides with the second, and that the second is a special case of the last. We investigate implications of this characterization; notably the Jonsson-Larsen simulation is shown to be sound, i.e. its existence implies trace inclusion.