Here’s the thing: both Pizza Sauce and Spaghetti Sauce are tomato-based sauces that are generally flavored with similar ingredients and seasoning.  Some say that Pizza Sauce should be uncooked while Spaghetti Sauce is cooked, but that’s not always the case.  Especially in the United States, many Pizza Sauces are cooked low and slow including this very recipe!   For us, the biggest difference between the two is that our Pizza Sauce is a little thicker and a little simpler than our Spaghetti Sauce.  It has no onions or meat - just garlic, tomatoes and simple seasoning.