What is the difference between a stand up paddle board and a kayak?

Stand up paddle boards and kayaks are both non-motorized water crafts. Typically a kayak is either sit on top or sit in water craft, the user paddles through the water from a seated position. Most kayaks are made from polyethylene but some kayaks are made from kevlar or fiberglass, there are also inflatable kayaks.  A stand up paddle board typically allows the user to paddle while standing up but they can also paddle while sitting if desired. Stand up paddle boards come in a variety of materials, hard paddleboards are made of fiberglass that is wrapped around a foam core, or polyethylene, inflatable paddleboards are made of stitching together pvc.