There is a difference! Marinara Sauce is "fresh" quick made sauce, where as Tomato / Spaghetti Sauce is a slower cooked more complex sauce.
Marinara Sauce is a more simple sauce, with fewer ingredients, and is made quickly. with a taste that is more that of fresh tomatoes.
Marinara is so easy to make from scratch for serving over pasta, once you learn how to make it, you'll fall in love with it!
Here's my personal Marinara Sauce Recipe. I make it in a huge batch and freeze the extra, so cut it in half for less.
It usually contains: whole Roma or plum tomatoes. (San Marzono are best if buying canned), I also love to make fresh sauce from my garden tomatoes all summer long. coarsly crushed by hand (or run through a food mill) to your desired "chunkiness consistency. It also contains:
garlic, crushed red pepper, and basil.
Tomato/Spaghetti Sauce being more complex, simmers longer and has a richer flavor with more ingredients.
A can of pureed tomatoes (or fresh tomatoes pureed) is the base, then seasoned with onions, small diced celery, garlic, Basil, Oregano, along with a few other ingredients, it is slow simmered. This sauce develops it's rich flavor over time.
Here's an authentic Tomato Sauce from Lydia's Italy.com I love watching her cook on T.V.! I wish I could sit in her kitchen while she does!