Subs or Submarine sandwiches are usually piled full of meat, cheese, all kinds of fixings and dressing like mayonnaise. The bread is an oblong Italian roll that measures anywhere from six inches to six feet. It is called a sub because it looks like a submarine.
Hoagies are best known in Philadelphia, Pennsylvania and in the south of the state of New Jersey. These are also associated with Italian-American culture. One of the theories about how this sandwich got its name is that Italian immigrants who worked at the Philadelphia Navy Yard, once referred to as Hog Island, were called “hoggies” which later became “hoagies”.
Hero sandwiches or Heroes come from my hometown New York City. They can be made with a variety of ingredients. They can have lots of meat and cheese or just vegetables and other things and they can be eaten warm or cold. It has been suggested that they got their name because it takes a heroic effort to eat one.
Grinders are best-known by those living in the New England states in the U.S. They too can be served warm or cold. You can choose to fill them with cold cuts and cheese, meatballs, even slices chicken breast or whatever you really like the best. The name might have been decided on because they require a lot of grinding or chewing while eating.