How are comets and asteroids alike and different?

They are similar in size and both orbit the sun directly. Comets contain a lot more ice, its composition is more like a dirty snowball, while an asteroid is more like a rock. The asteroids are generally closer to the sun, while comets originate from far out beyond Neptune, on the edge of the solar system and have been deflected off their large orbits into highly eccentric orbits that occasionally take them close to the sun.