There are two basic kinds of circular saws. The side winder is used for lightweight jobs and finishing work. Jig saw or saber saw. This saw is used to cut curving lines or make detailed cuts. When starting your cut from inside a piece of wood, you can drill a starting hole to cut openings in paneling, drywall, or counter tops.
Most models can accommodate a circle guide and angle cutting and ripping accessories.
This is generally used to cut openings in existing walls. It can rough-cut green wood, metal, leather, rubber, cloth, linoleum, and plastic. Sometimes called a bench saw, it can crosscut rip, miter, groove, and bevel. With accessories, it will cut dadoes, make moldings, and sand stock. Smaller table saws are good for general hobby and repair work.