Vacio is the traditional name in Argentina. Outside that tradition, butchers carry comparable beef cuts under different names — sometimes the same anatomical piece, sometimes a close cousin. The alternatives below are grouped by country so you can match what your local butcher actually carries.
Very similar cuts from the flank area — bavette d'aloyau is slightly more tender and from higher up the flank, while American flank steak is from lower down.
Similar cooking applications and the need to slice against the grain, but different muscles — flank is broad and flat while hanger is thick and cylindrical.
Both are flat, fibrous cuts from the belly area suited to marinating and slicing thinly, but flank is leaner and milder while skirt has more fat and a more intense flavour.
Adjacent cuts from neighboring primals; both are used for caldo de res and slow-cooked dishes in Mexico, though flank steak is leaner and firmer.
Both are thin abdominal-wall cuts with a layer of fat through them; vacío is the Argentine parrilla analogue to the Mexican taquería cut.