The difference between antigen and antibody is manifested in different principles, different functions and different test results. 1. Different principles: after entering the body, antigen can induce the body to have an immune response, and then produce antibodies. Antibodies are produced when B-lymphocytes in the body differentiate into plasma cells under the stimulation of antigens and produce a kind of immunoglobulin, which can bind to the corresponding antigen. 2. Different roles: antigen is a foreign substance to the body, can play a role in inducing the body to produce antibodies. Antibodies are produced by the body itself and can effectively eliminate pathogens that invade the body and usually have a protective effect on the body. 3. Different test results: Antigen detection can find out whether the body is infected with the corresponding pathogens. Antibody detection can find out whether the body of the corresponding pathogen resistance. Therefore, the difference between antigen and antibody is manifested in different principles, different functions and different detection results.