I will choose (A) Star and planet and (B) Asteroid and comet.
Stars are massive celestial bodies that produce light and heat through nuclear fusion in their cores, while planets are smaller objects that orbit stars and do not generate their own light. Stars are formed from collapsing clouds of gas and dust, while planets develop from the leftover material in a star's protoplanetary disk.
Asteroids are rocky, metallic objects that orbit the Sun, mostly found in the asteroid belt between Mars and Jupiter, and are remnants from the early solar system. Comets, on the other hand, are composed of ice, dust, and rocky material, and originate from the outer regions of the solar system, often forming tails when they approach the Sun due to sublimation.