There are four categories for lentils: red/yellow, brown, green and specialty. Lentils are a good protein and carbohydrate source, and they are simple to prepare because they do not need soaking like dried beans.
Red or yellow lentils are similar to each other and do not hold shape when cooked. These work well to make mashes or to add thickness to soups or stews. Brown and green lentils do hold shape during and after the cooking process, and they work well as a side dish or mixed into a casserole or salad.
Specialty lentils include black beluga and green lentils. The black beluga is high in antioxidants, holding it shape well during and after cooking. Green lentils are from France, where they are known as Le Puy lentils, and they are considered the best of the lentils, making them more expensive.