Marinara sauce is a quick sauce. Tomato sauce, on the other hand, is a more complex affair.
Marinara sauce is a quick sauce, seasoned only with garlic, crushed red pepper, and basil. It is best when made with whole San Marzano or plum tomatoes, coarsely crushed by hand or passed through a food mill. Marinara can be left chunky; the texture of the finished sauce is fairly loose, and the taste is that of fresh tomatoes.
Tomato sauce, on the other hand, is a more complex affair, starting with pureed tomatoes seasoned with onion, carrot, celery, and bay leaf, and left to simmer until thickened and rich in flavor. Sometimes a piece of fresh pork meat is added for additional flavor. The taste is sweeter and more complex.