[arrrg]

Vinegar and sugar are the two other vital components of tomato ketchup, with vinegar probably being the more characteristic of the two. (Tomatoes are naturally somewhat sweet, so you are always going to have some sweetness in your tomato sauce as a flavor component.)

Both are either used not at all in tomato sauce or used in much, much lower doses. (I actually have sometimes used very low doses of balsamic vinegar in my tomato sauces but it’s an atypical ingredient. Sometimes adding carrots, honey or just a bit of sugar is recommended if your tomatoes are particularly sour and lacking in sweetness but that’s more as a workaround to hide not so tasty tomatoes. I have also done that in the past but we are talking about adding a pinch of sugar or a drop of honey, not having sugar as the third entry on your ingredients list.)

Obviously, the texture of ketchup is also very smooth while tomato sauce can have many different textures, from completely smooth like ketchup to with substantial vegetable chunks. Depending on how long you cook the sauce those chunks will also be more or less soft. Also, tomato sauce can and probably often is much less thick than tomato ketchup and tomato sauce often has quite a bit of added fat (typically butter or olive oil or both).

Ketchup is also typically served cold and tomato sauce hot but that’s more like the default. Both can go either way.

So, yeah, I would say there are a lot of substantial differences between tomato ketchup and tomato sauce beyond just how concentrated the tomatoes are.

But maybe we are talking past each other and what you call “tomato sauce” is actually something else entirely.