Why is an carrot more orange than an orange?

Because carrots contain more beta-carotene (which is converted in the body to Vitamin A). A class of chemicals called carotenoids creates many of the bright pigments in plants in the yellow-red range. Beta-carotene is a bright orange color. Carrots are well-known for their beta-carotene content, while oranges are not.

It is most likely because of the different vitamins and how much of them are in each food.