Potato
A nasty little toxic root composed mainly of starch. You're better off eating a twinky. The skin has nutrients... a nominal amount of potassium, more than a banana--high levels of potassium will damage dysfunctional kidneys, but potatoes are otherwise safe. Also, otherwise devoid of nutritional value.
Sweet potato
Similar to the potato, with a better flavor and much higher nutrient load. The orange color comes from carotine. Higher in fiber and micronutrients than a standard potato.
Sugar pumpkin
Easy to convey. Contains a fair level of nutrients, but has a somewhat bland taste. Best enhanced with sugar. Somewhat stringy texture.
Long island cheese pumpkin
Shape makes it more difficult to convey than the sugar pumpkin; but its flavor has higher culinary value. Increased level of sugars, as well as a higher nutrient load than the sugar pumpkin. The meat is smoother and less fibrous, and a deeper orange due to higher levels of carotine.
Somehow, I think the list goes on and I don't have it. Standard bland or bitter-nasty collard greens, cauliflower (holy crap tasteless), lettuce, and broccoli just don't stand up to the fine tastes and nutrient loads of butternut squash, tomatoes, or japanese kyoto red carrots or kamo eggplant.