How are various bodies in the solar system similar and different?
Lets start with the sun.
The sun is a star in the middle of our solar system made out of plasma. It is very different from the other planets in many ways. It's the only one where fusion occur because of high pressure, it's the hottest celestial body, it has the strongest gravity ect. There is not many similarities between the sun and the planets.
Amongst the planets there are more similarities. They are all orbiting the sun, it's the dominant celestial body in its orbit, basically stuff that defines a planet.
There are also many differences like if it's a terrestial planet (mercury, venus, earth, mars) or a giant planet (Saturn, Jupiter (gas giants), Uranus, Neptune (ice giants)).
Then we also have asteroids and moons. Most asteroids and moons are similar to eachother but very different from other celestial bodies. They are smaller and miss an atmosphere.