The main difference between a tripod and a monopod is the number of legs. A tripod has three legs and a monopod has one leg.
A tripod is generally more stable than a monopod and is suitable for long exposure photography, low-light photography, and situations where you need your camera to be completely still. The three legs of a tripod provide a stable base for your camera, allowing you to shoot at slower shutter speeds without introducing blur.
On the other hand, a monopod is more portable and easier to carry than a tripod. It is ideal for situations where you need to move around quickly or where a tripod is not allowed, such as in crowded areas or events. A monopod can also be used as a stabilizer to help you shoot at slower shutter speeds, although it is generally less stable than a tripod.