<human>:  What is the difference between a carbohydrate and a lipid?
<bot>: The difference between a carbohydrate and a lipid is their chemical composition. Carbohydrates are composed of carbon, oxygen, and hydrogen molecules, while lipids are composed of carbon, hydrogen, and oxygen molecules, as well as phosphorus and nitrogen. Carbohydrates are generally found in plant products and have a higher water content than lipids, which makes them easier to break down. Lipids on the other hand, are typically composed of fatty acids, triglycerides, and sterols, and are found in animals and plants. Carbohydrates are used as a source of energy, while lipids are used to synthesize hormones and vitamins.