The planets have different movements. A rotation, revolve on themselves around the axis. This determines the length of day on the planet. A revolution, planets orbits around the Sun every orbit is the planet's year. Each planet takes a different time to complete.
The compacts are in the core. Gases, if any, formed on the surface of an atmosphere. Mercury, Venus, Earth, Mars are small, rocky planets with high density. They have a slow rotation, moons few (or no) and quite round. Jupiter, Saturn, Uranus and Neptune, the gas giants, are huge and light, made of gas and ice. These planets revolve faster and have many moons, and rings equatorial bulge.