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How are the inner terrestrial planets different from the outer giant planets?

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Illustration showing the eight planets of the solar system in order from the Sun-Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune-depicted to scale by size, with labeled diameters in miles and kilometers. The Sun is partially visible on the left for comparison. — Solar system The planets (in comparative size) in order of distance from the Sun.

The eight planets of the solar system are divided into two distinct categories based on their composition, density, and physical characteristics, a difference largely attributed to the temperature gradient in the early solar nebula.123

Inner Terrestrial Planets

The four inner planets—Mercury, Venus, Earth, and Mars—are characterized by:
* Composition: They are rocky bodies with high densities (greater than 3 grams per cubic cm).12
* Structure: They are relatively small, possess solid surfaces, and lack ring systems.1
* Moons: They have few or no natural satellites.1
* Formation: They formed close to the Sun where temperatures were too high for volatile substances like water and ammonia to condense into ice.3

Outer Giant Planets

The four outer planets—Jupiter, Saturn, Uranus, and Neptune—are characterized by:
* Composition: They are massive, low-density objects (less than 2 grams per cubic cm) composed primarily of hydrogen and helium, or a mix of ice, rock, hydrogen, and helium.14
* Structure: They lack solid surfaces and feature extensive ring systems.12
* Moons: They possess many natural satellites.1
* Formation: They formed beyond the "snow line," allowing them to accumulate enough mass to retain large amounts of hydrogen and helium from the solar nebula.3