All immunogen are antigen but all immunogen?

Not all antigens are immunogens. An immunogen is an antigen that is capable of stimulating an immune response, while an antigen is any substance that is recognized by the immune system. Some antigens are not immunogenic, either because they are not able to be processed by the immune system or because they do not contain the necessary molecular structures to trigger an immune response. For example, some polysaccharides are antigens but are not immunogenic, while some proteins are both antigens and immunogens.