Reply by Cosmicsniper

Mark: An actual planer gets one side of a board parallel to another. That’s its purpose. A jointer doesn’t really plane anything in that sense, and thus the jointer/planer name is a misnomer (it just makes one plane). You would use a jointer to make one face flat for a reference edge. From there you can use a variety of tools to square and thickness a board.

-- jay, www.allaboutastro.com