replicate and duplicate do slightly different things: Duplicate makes a copy of the object and sticks it in exactly the same place as the source. Replicate first duplicates the object, THEN performs the last transformation that you did to the object (move, resize, rotate). Use replicate (and its big brother, multi-replicate) when you want to position/resize/rotate a series of identical objects in identical ways. Such as making the steps of a spiral staircase. Create, rotate, replicate, replicate, replicate.