Canned tomatoes are often canned on their own, with just the addition of a bit of sugar and some salt. Occasionally, other seasonings like basil are included, but that is usually noted on the can. Stewed tomatoes usually have other seasonings involved, whether homemade or canned. They are usually slightly sweeter than canned tomatoes and may have other herbs, spices, and vegetables added. Also, great homemade stewed tomatoes shouldn’t be cooked down until they become mush; they are cooked just enough to caramelize a bit and soften the tomatoes, but they should still have some texture to them.