1.) Comets are icy objects while Asteroid is rocky fragments.
2.) Comets origin in Oort Cloud while Asteroid came from Main Asteroid Belt.
3.) The both have varied/irregular Shapes.
4.) Comets orbit is relegated to either a cloud or belt on the solar system while asteroid orbit is in the sun in a tightly packed belt located between Mars and Jupiter
5.) Comets contains ice , frozen gases , and other matter while Asteroid contains Silicate , Iron & Nickel.
6.) Comet has orbital period of 1-100years while Asteroid have 1-10years .