Tomato sauce (also known as Neapolitan sauce, and referred to in Italy as Salsa di pomodoro) refers to any of a very large number of sauces made primarily from tomatoes, usually to be served as part of a dish (rather than as a condiment). Tomato sauces are common for meat and vegetables, but they are perhaps best known as sauces for pasta dishes.
Neapolitan sauce, tomato sauce and Salsa di pomodoro are all the same thing. 