a hero and a sub

Reader's Digest 10月号の記事 'Life In These United States' からの引用です。

Scanning the diner's menu, I noticed that the offerings included both a hero and a sub.
"What's the difference?" I asked my waitress.
"I don't know. I'll find out." She walked into the kitchen and returned a minute later. "They're both exactly the same."
"OK, I'll have one."
Grabbing her pad and pencil, she asked, "Which one do you want?"

私は "hero" は中に挟む具材の種類が最も多いのかと思っていました。 どっちも同じなら、何故メニューに両方の名前で載せているのでしょうか？　"hero" を辞書で見ます。

・Oxford English Dictionary: (also submarine, submarine sandwich, sub (all North American English)) a long bread roll split open along its length and filled with various types of food
・Collins Dictionary: a large sandwich, usually consisting of a small loaf of bread or long roll cut in half lengthwise and containing a variety of ingredients, as meat, cheese, lettuce, and tomatoes
USAGE
The terms hero sandwich and hero, once largely associated with the New York City and Northern New Jersey area, are now too widely spread to warrant a specific regional label. This same sandwich is also called a submarine or a sub, esp. in the Northeastern and North Midland U.S., although this use has spread south along the Atlantic coast and as far west as Los Angeles. torpedo, though less common, has also spread to various regions. The sandwich is called a grinder, chiefly in New England and the Inland North, though this use has spread to the South and West. spuky is restricted to the Boston area, while wedge is a common synonym in Rhode Island and coastal Connecticut. hoagy (or hoagie) is used chiefly in New Jersey and Pennsylvania, esp. Philadelphia, though it too has spread to other regions. poor boy is chiefly New Orleans use, originally referring to a somewhat different sandwich in which distinct sections of fillings represented the courses of a meal. cuban sandwich, usually referring to a grilled sandwich with ham, pork, cheese, etc., is chiefly used in Southern Florida as well as the New York City area
米国の各地によって色々な名称が使われているのですね。