Well, the main difference seems to be that of sexual reproduction versus that of asexual reproduction. Fruits are produced by flowering plants that produce ovules fertilized by pollen. The advantages of this type of reproduction are to insure a wide cross section of traits available from the general population of plants. Sexual reproduction combines the traits from two genetically different plants, providing a variety of expressions of different traits. Asexual reproduction, as is found by plants producing tubers, produces offspring plants that are genetically identical to the parent plant. This is good if the parent plant is competitive to the general environmental conditions, but bad if the plant is not. Tubers are used by plants to survive winter and the dry months and to provide energy and nutrients for regrowth during the next growing season.