Pathogens are the disease causing agent while antigens are found in the antibodies that fight against the pathogens. So in short, no they aren't the same.
Lymphocytes
pathogens antigens
all wbc produce antibodies to attach the the pathogens antigens.
your body produces antigens to fight against the pathogens and imune you agaist diseases.
The molecules on pathogens that enable the immune system to distinguish one kind of pathogen from another are called antigens. Antibodies destroy pathogens by binding to the antigens on the pathogen.
Antigens
phagocytosis
Antigens are important because they trigger responses to pathogens by the immune system. Without them, no prevention against pathogens would take place.
The process of immunity is to produce specific antibodies that bind to antigens on the surface of pathogens. =]
When pathogens enter the body, they begin to cause disease. Path=disease+ gen=to make (or generate).
The short answer is that the Type B patient has antigens for that specific blood type, so when type A is mixed with the type B, the antibodies in the B blood kill the A blood cells, making it useless.