When I think of steak au poivre, I see a slab of strip steak, coated with cracked pepper, seared to a dark crust on the outside but still very rare on the inside. Maybe a pan sauce, and maybe the meat sliced for presentation, but pretty much that's it: solid meat coated with pepper and cooked.
Ginger steak, on the other hand, makes me think of thin slices or strips of beef (maybe flank steak), stir-fried with julienne ginger and vegetables (snow peas, bell pepper, Asian vegs like water chestnuts and bamboo shoots), and with a cornstarch-thickened sauce.
Two very different dishes. Both have steak and both have "pepper" but only one has ginger. Neither has a marinade for the meat.