Confused Dear Confused, This is indeed a very confusing issue. Botanically, the difference between fruits and vegetables lies in the part of the plant we eat, not in how we use them as food.
Fruits come from the ripened ovary of a flowering plant.
What we eat is the fleshy covering surrounding the seed or seeds. Most fruits are sweet because they contain a simple sugar called fructose, whereas vegetables, which usually have much less fructose, are much less sweet. The reason many fruits are sweet is to encourage animals to eat them, and thereby spread the seeds. By contrast, plants need their roots, stems and leaves to survive, and so by not being sweet, they diminish their appeal. Some fruits, for example tomatoes and avocados, do not have much fructose and are not so sweet.