The question is not well-defined enough to answer.
One common division is between "terrestrial" (rocky) planets and "jovian" (gas giant) planets. Some people make a distinction between "gas giants" (Jupiter and Neptune) and "ice giants" (Uranus and Neptune).
Rocky planets and gaseous planets.
Astronomy, Glaciology, exo-planets.
They are mostly different kinds of gas.
"solar system" is the term used to describe planets orbiting a star. We know that planets also orbit binary and tertiary star systems, these would be different kinds of solar systems.
In the solar system, we have a star, planets, dwarf planets, asteroids, comets, meteors, and human debris. (such as old satellites, probes, etc.)
Planets, moons, and asteroids, comets and gases, dust, particles etc.
Extraterrestrial are unknown humans. They are humans, but different kinds from different planets. Like aliens and UFOs. The scientific community think this is true. They think they come from planets beyond Earth...
The solar system.
Jupiter, Saturn, Uranus, and Neptune are often referred to as gas giants. They are composed mostly of hydrogen and helium, with no solid surface. These planets are also much larger in size compared to the terrestrial planets like Earth and Mars.
The inner planets, also known as terrestrial planets (Mercury, Venus, Earth, Mars), are smaller, rockier, and have solid surfaces. The outer planets, also called gas giants (Jupiter, Saturn, Uranus, Neptune), are larger, primarily made of gas, and have no solid surface. Both sets of planets orbit the Sun, but inner planets are closer to the Sun and have shorter orbital periods, while outer planets are farther away and have longer orbital periods.
Planets have moons. Stars have planets. Galaxies have stars. Galaxies tend to actually be a supermassive black hole at the center so as far as the central object being orbited it is usually a black hole.
The planets in our solar system are categorized into two main types: terrestrial planets (Mercury, Venus, Earth, Mars) which are rocky and relatively small, and gas giants (Jupiter, Saturn, Uranus, Neptune) which are composed mostly of gases and have thick atmospheres. Additionally, there is a category of dwarf planets, such as Pluto and Eris, which don't meet all the criteria to be considered full-fledged planets.