Lactoferrin and immunoglobulin differ in their definitions, sources, and roles. 1. Definition: Lactoferrin is an iron-binding glycoprotein belonging to the transferrin family, while immunoglobulin is an immunologically active molecule, which is a collective term for globulins that have antibody activity or a chemical structure similar to that of antibodies. 2. Source: Lactoferrin is more abundant in cow’s milk and colostrum, and less abundant in tears, saliva, gastrointestinal secretions, tracheal secretions, etc. Immunoglobulin is produced by the body after stimulation by external antigens, and it mainly exists in the blood, and infants can also get part of it from breast milk. 3. Role: lactoferrin has antibacterial activity, but also to a certain extent with immunomodulation and anti-tumor effects, but also to maintain the iron content of cells has an important role. Immunoglobulin mainly plays a role in resisting the invasion of pathogens, but also can lead to hypersensitivity reactions and regulate the immune response. Lactoferrin and immunoglobulin are both proteins, but their roles and other aspects are completely different and should be distinguished.