In general, the brown and green varieties retain their shape well (some more fully than others), whereas the hulled and, most particularly, split red and yellow lentils tend to disintegrate and, therefore, are best for soups or in applications where they'll be pureed.You can substitute other lentils, though their texture and flavor will differ some. French green lentils can sub in salad and side dishes but red lentils, which also fall apart during cooking, are a better substitute in a soup.Brown and green lentils are the most popular types in many countries. Red lentils/Egyptian lentils (usually split and have the most earthy flavor) Brown/Spanish pardina lentils. French green lentils/puy lentils (which have a dark, speckled, blue-green color)These can be pale or mottled green-brown in color with a glossy exterior. They have a robust, somewhat peppery flavor. Green lentils generally take the longest to cook, upwards of 45 minutes, but they keep a firm texture even after cooking. This makes them ideal for salads and other side dishes.