A comet is a frozen collection of rocks, gases and dust that orbits around the sun, while a meteor is a piece of debris that comes into contact with a planet's atmosphere. Before it collides with a planet, a meteor is called a meteoroid.
When a meteor collides with a planet and travels through the atmosphere, it burns up. A meteor that is burning up in Earth's atmosphere is sometimes called a shooting star. The debris left by a comet during its orbit can cause meteor showers when Earth's orbit intersects with the orbit of the comet. Meteors most often fall during yearly meteor showers.