What is the difference between sauce and ketchup?

Traditionally, in the US, tomato ketchup was prepared with tomatoes, sugar, vinegar/ acetic acid and spices. It is used as a dressing or table condiment to be consumed with chips, burgers, etc. Ketchup is cold and is never heated as a rule.

Tomato sauce, on the other hand, is made from tomatoes, oil, meat or vegetable stock and spices. Vinegar is not usually used. Sauces are generally served hot. Most manufacturers insist that ketchup is made with spices, onions and garlic while sauce is generally made without spices.