Mousse, mousseline, and quenelle are all types of forcemeats made with meat, fish, or vegetables that are pureed and bound together. A mousse is made with cooked ingredients mixed with a binding agent like gelatin and cream. Mousseline uses uncooked meat or fish pureed with egg whites and sometimes cream, then set by cooking. Quenelles are shaped from a raw fish forcemeat mixed with egg whites, then poached before serving. All three can be made with different ingredients but follow a similar preparation process of pureeing and binding ingredients.