Answer:
Asteroids and comets have a few things in common. They are both celestial bodies orbiting our Sun, and they both can have unusual orbits, sometimes straying close to Earth or the other planets. They are both “leftovers” — made from materials from the formation of our Solar System 4.5 billion years ago. But there are a few notable differences between these two objects, as well. The biggest difference between comets and asteroids, however, is what they are made of.
While asteroids consist of metals and rocky material, comets are made up of ice, dust, rocky materials and organic compounds. When comets get closer to the Sun, they lose material with each orbit because some of their ice melts and vaporizes. Asteroids typically remain solid, even when near the Sun.
Right now, the majority of asteroids reside in the asteroid belt, a region between the orbits of Mars and Jupiter which may hold millions of space rocks of varying sizes. On the other hand, the majority of comets are in the farthest reaches of our Solar System: either 1. in the Kuiper Belt — a region just outside the orbit of the dwarf planet Pluto that may have millions of icy comets (as well as many icy dwarf planets like Pluto and Eris); or 2. the Oort Cloud, a region where trillions of comets may circle the Sun at huge distances of up to 20 trillion kilometers (13 trillion miles).