Leave it to the to uncover the hidden treasures of the Internet. Recently, they were gabbing about Google's nutrition comparison tool, which was quietly at the end of 2013 and escaped us here at The Salt.
Using this clever little tool is as simple as searching for two types of food, preceded by the word "compare." The word "vs." between the two foods also seems to work for some comparisons but not every single one.
So, for example, say you want to compare the calories, sugar content and nutrients of mashed potatoes and sweet potatoes? Just type in "," and boom, you get photos and an elegant chart revealing that sweet potatoes have 4.2 grams of sugar per 100 grams, compared with 0.5 grams in mashed potatoes. Scroll down and you'll see that sweet potatoes kill mashed potatoes in vitamin A, potassium and calcium content.
As you contrast ingredients, perhaps out of sheer curiosity, perhaps to design a meal plan, you'll learn a lot by playing around with the preparation and cooking method of the food. Tweak the mashed potatoes to "potato, mashed, with milk and butter," and unsurprisingly, the fat content jumps up.
For the rest of the story: http://www.npr.org/blogs/thesalt/2014/03/24/291963536/apples-vs-oranges-google-tool-offers-ultimate-nutrition-smackdown