Yes, pressure cooker and pressure canner work the same. They use high pressure to reach higher temperatures - that higher temperature kills more bacteria.

A pressure canner still might be useful, because most pressure cookers aren't as big as the canners. I only use the cooker because I already had one way before I thought about canning stuff and because here in germany most canning still is done with hot water rather than in steam and therefore pressure canners are harder/more expensive to come by.