Inoculation vs. vaccination
Both are forms of immunisation. 

Inoculation is exactly that. A live organism is introduced in a controlled way, so as to minimise the risk of infection, and is essentially the same process followed by many people in history.  It is inherently risky.

Vaccination is introducing a weakened version of the pathogen, so that the immune response is triggered and the body is prepared to fight the actual pathogen if necessary. This was pioneered by Edward Jenner, wherein he noticed that cowpox (related to smallpox) immunised the milkmaids against smallpox.