A slip bobber is an oval or round foam piece with a 3- or 4-inch plastic tube mounted through it. You pass the fishing line through the stick and either use a bobber stopper or tie a knot in your line at the depth you want it to stop. These are the best choice for depths over 5 feet as they are easier to cast.
A round bobber is a hollow plastic ball with recessed hooks on the top and bottom. There is a spring-loaded button that, when depressed, expose the hooks used to attach the line. Because round bobbers do not slide freely on your line, they are easily used to a depth of about 7 or 8 feet. At greater depths, they are difficult to cast.
A spring bobber is an oval or round piece of foam with a 3- or 4-inch plastic tube mounted through it. It has a small hook on the bottom that the line wraps around. There is a spring that must be depressed to access the hook. The spring bobber, which don't slide freely on the line, is only good to a depth of 7 or 8 feet. They are difficult to cast at greater depths.
A peg bobber is made from small foam ovals or circles that have a vertical line cut halfway through them. You place the line in this cutout, then a peg is placed down into the cutout, locking the line in place. Peg bobbers are most often used in ice fishing, because they can easily be adjusted to fish at different depths.