Italians call the sauce for spaghetti whatever sauce they are using! Marinara, carbonara, sugo di pomodoro, ragú, and others are common! The American term "spaghetti sauce" in the United States generally refers to a tomato based sauce (similar to a sugo di pomodoro), but it often includes meat and is served over spaghetti. You won't find a specific sauce under the name "spaghetti sauce" in Italy since there are many upon many sauces that are served with spaghetti.