Difference Between Legumes and Lentils. Legumes are a family of plants called Fabaceae, or the fruit of this type of plants, which is referred to as pod. Some common legumes eaten in different parts of the world are clover, Alfalfa, peas, lupins, lentils, peanuts etc. Thus, it is clear that lentils are a type, or subcategory of legumes. Legumes are full of proteins and fibers which is why they are a staple food of populations that are vegetarians. People often remain confused by the differences between legumes and lentils.