word meaning - Tomato ketchup Vs Tomato sauce

Dictionaries did not help me. Collin's writes tomato sauce = tomato ketchup but not vice versa. There tomato ketchup is ketchup flavored with tomatoes. Furthermore, ketchup is sauce!

MM says ketchup is sauce and so does OALD. Times of India has good note on that but is understood and written by a non-native and so not sure. Wikipedia says ketchup is a table sauce. Phew!

What I understand (looking at the ingredients) - tomato sauce contains no garlic/onion in any form whereas tomato ketchup has them.

Enlighten me please.

Answer

Strictly speaking, the dictionaries are correct: Tomato ketchup is a form of tomato sauce, since a sauce is simply "a liquid, semi-solid, or cream food served on other foods".

Ketchup is very specifically a sweetened and thickened tomato puree that usually contains vinegar, onions, garlic, and other spices. The exact composition varies between manufacturers, but it always contains sugar and almost is always thickened, and it contains no lumps or non-blended components. The tomatoes are usually cooked completely before blending. It is most often eaten with fried foods, meat loaf, and hamburgers.

In American English, "tomato sauce" is generally distinct from "ketchup". "Sauce" would be the kind of tomato product you would eat with spaghetti, or put on pizza, or eat with chicken parmigiana. It generally does not contain much added sugar or other "sweet spices", and it may or may not be completely blended. The tomatoes may or may not be cooked before blending. (Wikipedia also notes an "incomplete" form of tomato sauce, which is simply blended tomatoes with no other additives other than salt. It is used as a base for more complete sauces and is not intended to stand alone.)

Ultimately, in American English, the difference comes down to application. Ketchup will rarely be eaten with pizza or spaghetti, and few people would eat tomato sauce with fries or hot dogs. It's not so much a matter of people deliberately distinguishing the words as that the distinction arose organically.