The Ehrlich-Schwoebel (ES) barriers to the diffusion of adatoms (Pd,Ag and Cu) on different bench terraces of fcc Cu are compared by molecular dynamics computation. The computation reveals that: 1) For both heteroepitaxial and homoepitaxial systems, the ES barriers increase similarly with the increase of bench terrace height until a certain height is reached. 2) The ES barrier of adatom Pd is the biggest, the second one is that of adatom Cu, and the smallest one is that of adatom Ag for the hopping diffusion mechanism, while the ES barrier of adatom Ag is the biggest, the second one is that of adatom Cu, and the smallest one is that of adatom Pd for the exchange diffusion mechanism. 3)The ES barrier of exchange is lower than that of hopping mechanism in most cases of bench terraces.