Both pressure cookers and pressure canners use the same concept of building pressure within the pot in order to create a high, moist heat.
Although pressure cookers and pressure canners look somewhat alike, canners are typically larger and come with racks that sit inside the canner to hold jars during the process of preserving food. Canners are also designed to maintain heat and pressure, unlike pressure cookers.
A pressure cooker enables one to cook a roast that would normally take three hours in as little as 30 minutes. A pressure canner allows preservation of home-grown food.
While a pressure cooker is a time saver when preparing meals, both are economical for their given purpose.
In the 1670s a French lab assistant by the name of Denis Papin invented the first pressure cooker. The principle design is what eventually led to the invention of steam engines.
Pressure cookers and pressure canners have the ability to cause serious injury if proper caution is not taken during operation.
Denis Papin called his first pressure cooker invention a "steam digester".