What differentiates a comet from an asteroid?

The distinguishing characteristic between comets and asteroids lies in their composition. Comets are primarily composed of ice, dust, and other volatile compounds. This icy composition allows comets to develop a visible atmosphere or coma and a tail when they approach the Sun, due to the sublimation of their ice as temperatures rise.

On the other hand, asteroids are predominantly made of rock and metal. They lack the significant amounts of ice that characterize comets. Therefore, the presence of ice and dust in comets, alongside their unique behavior as they approach the Sun, is what sets them apart from asteroids.