Definition
What is a fruit?
A fruit is defined as the developed ovary of a seed plant with its contents and accessory parts, as the pea pod, nut, tomato, or pineapple. It is the edible part of a plant developed from a flower, with any accessory tissues, as the peach, mulberry, or banana. A fruit is the often sweet and fleshy part of a plant that surrounds the seeds, although some fruits like berries bear the seed on the outside of the fruit.
What is a vegetable?
All other edible plant parts are considered vegetables. A vegetable is an herbaceous plant cultivated for an edible part, such as the root of the beet, the leaf of spinach, or the flower buds of broccoli or cauliflower.
Examples of fruits and vegetables
Here's an interesting list of fruits that are often thought to be vegetables:
tomatoes
cucumbers
squashes and zucchini
avocados
green, red, and yellow peppers
peapods