Ganymede is the biggest and the most massive moon of the planet Jupiter. It has a metallic core. It moves in an orbital path around the planet Jupiter and orbits every 6-7 days. Half of the moon is comprised of silicate rocky materials and half of it is made up of water ice. Out of all the moons, Ganymede has the highest rock composition.
Europa is one of the moons of Jupiter. It is even smaller than the earth's natural satellite (moon). The core of this moon is made up of iron and nickel, along with some silicate materials but they are extremely in a lesser amount in comparison to the earth's core. Europa's surface is comprised of ice and water is present in a significant amount below the surface.
