What's the difference between a "canvas board" and a "stretched canvas"? A canvas board is most likely cotton canvas glued to a hard piece of paperboard or cardboard and primed with gesso, a sort of sealer. You'll find that canvas board is a bit less expensive than stretched canvas, so it is great for practicing. To display a canvas board painting attach a stick on hanger thingy to the back. (yes, that's an artist's term).

Stretched canvas is typically linen or cotton stretched over a rectangluar or square wooden frame and is then gessoed (sealed) to prep it for painting. It is typically a more expensive canvas than a canvas board. The more a canvas is prepped, the higher the cost.