Differences in popular usage
Fruits and vegetables are vegetarian as well as vegan, hence constitute a big part of the staple diet in almost every household.
Traditionally, most people categorize "vegetables" as foods that are eaten as part of a meal's main course and "fruits" as foods that are eaten for dessert or as a snack.
Most fruits are sweet with bitter seeds, because they contain a simple sugar called fructose, while most vegetables are less sweet because they have much less fructose. The sweetness of fruit encourages animals to eat it and spit out the bitter seeds on the ground so they spread and further the plant's life cycle.