I think the terms are just different for different countries, but in the US, tomato sauce is just tomatoes and water, whereas ketchup has seasonings, such as the vinegar someone mentioned, and also onion powder, in the Heinz brand anyway 
As for me, either plain ketchup on a bun, or for a bunless hotdog, peanut butter and cheddar cheese melted together on top is the only way to go

As for me, either plain ketchup on a bun, or for a bunless hotdog, peanut butter and cheddar cheese melted together on top is the only way to go
