I have researched far and wide and could not find a specific reason why some Italians call it gravy rather than sauce. The best I could do was that gravy takes all day to simmer on the back burner while sauce is done quickly.

Any other thoughts?

And here is the recipegravy

Meatball Ingredients:

2 pounds lean ground beef
4 eggs
2 cups (approx.) seasoned bread crumbs
1/2 cup grated Pecorino Romano cheese
2 cloves of garlic, chopped
1/2 tsp. salt
1 tsp. ground black pepper
1 tablespoon fresh parsley, chopped

In a bowl, mix all ingredients for the meatballs with hands until well blended.  Form about 16 meatballs (or more if you make them on the smaller size) and place on a platter.  In a frying pan, add olive oil and when hot, add meatballs, leaving enough room to gently turn each for browning (use a wooden spoon).  Cook on medium heat until browned; repeat until all meatballs are browned.  Do not overcook as they finish cooking in the sauce.  Place meatballs on a clean platter. 

Gravy ingredients

1/4 cup oil
1 clove garlic, chopped
1 medium onion, chopped
1 pound sweet or hot Italian sausage links (optional)
3 large (35 ounce) cans Italian tomatoes — Pastene Kitchen Ready are fine
1 (6 ounce) can tomato paste
1 can (use tomato can) of water
1/4 teaspoon salt
1/4 teaspoon ground black pepper
1 Teaspoon fresh parsley, chopped
Fresh basil, if desired

In an 8 quart saucepan, heat the olive oil and saute garlic and onion until lightly browned and fragrant, about 2 minutes.  Add the sausage links and brown. 

Add 3 cans of tomatoes, tomato paste, 1 can water, salt, pepper and parsley, and fresh basil, if using. Bring to a gentle boil over medium heat and cook for 15 minutes, stirring often.  After 15 minutes, carefully add the meatballs, stirring with a wooden spoon to avoid breaking meatballs.  When all meatballs have been added, reduce heat to low, partially cover and cook for 2-1/2 hours, stirring every 15 minutes or so to prevent sticking.  If sauce seems too thick, add a little more water.

Serves 6 to 8