A canner has room for at least 4 quart jars, standing upright. It also has an adjustable weight so the canner can be set for 5, 10 or 15 pounds pressure.
You can cook in a pressure canner---I make stock in mine all the time. You cannot can in an electric pressure cooker, except for the one Ball makes, which only does high acid foods.
I just haven't been the same
since that house fell on my sister.