Another observation I have made in my research and reading on fruits and vegetables and their health benefits is that they never seem to be separated. In other words, fruits and vegetables are usually talked about in the same breath when discussing the health benefits of plant-based foods. However, in practice, I usually suggest taking a "balanced" approach to fruits vs a more "generous" approach to vegetables. Why? Consider the following 3 distinctions (botanical, culinary and sugar) used to separate fruits and vegetables.
Botanical: Botanically speaking, a fruit is a seed-bearing structure that develops from the ovary of a flowering plant, whereas vegetables are all other plant parts, such as roots, leaves and stems.
Culinary: A lot of foods that are (botanically speaking) fruits, but which are savory rather than sweet, are typically considered vegetables by chefs.
Sugar: Most fruits are sweet 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 thereby spread the seeds.
Simplified: if I had to pick one: fruits or vegetables, I would pick vegetables. Why? Because, using the culinary/sugar distinction (which I recommend), vegetables provide the plant food benefits without the increased sugar (which most of us need a little less of in our diets). Having said that, fruits provide an array of their own set of beneficial plant nutrients (i.e. phytochemicals) so we should always eat both fruits and vegetables...but we can moderate our fruit intake in favor of vegetables. (FYI: even the USDA MyPlate model for anyone over age 3 suggests that your vegetable intake should be 1-3 servings greater than your fruit intake daily - see http://www.cdc.gov/nutrition/everyone/fruitsvegetables/howmany.html)