Final answer:
Active immunity is when the body generates its own immune response, either through natural infection or vaccine-induced. In contrast, passive immunity is the direct transfer of antibodies, either naturally through maternal transfer or artificially via antiserum injections.
Step-by-step explanation:
The difference between active immunity and passive immunity lies in how the protection against pathogens is acquired. Active immunity occurs when an individual develops their own adaptive immune response to a pathogen. An example of natural active immunity is when a person contracts an illness and their body fights off the infection, thereby building memory cells specific to that pathogen. On the contrary, artificial active immunity is when a vaccine is introduced into the body, stimulating an immune response without causing the full-blown disease, such as the vaccines for measles or polio.
Passive immunity, however, involves the direct transfer of protective antibodies to an individual. In natural passive immunity, a baby receives antibodies from the mother through the placenta before birth or through breast milk after birth. Artificial passive immunity is the direct introduction of antibodies into the body, for instance, through an antiserum injection to treat snake bites or rabies.