There's so many different types of soy sauce. The aged ones have even more umami, more deepness of flavor. There's white soy sauce, if you've never seen it it's actually clear in color. It tastes like soy sauce but it's white and that's used on dishes you don't want to see the darkness. Like wine, the darker it goes the deeper in flavor but funny enough, the dark, dark soy sauce isn't as salty, it's just deeper in flavor.