What is the reason for the development of the interior layers of these two planets?

The development of the interior layers of planets like Earth and Mars is primarily influenced by their size, composition, and thermal evolution. Larger planets can retain heat longer, allowing for processes like differentiation, where heavier materials sink to form a core while lighter materials create a mantle and crust. Additionally, factors such as volcanic activity, tectonic movements, and the presence of water contribute to shaping the geological structure of these planets over time. Variations in their formation and environmental conditions also play a critical role in their interior layering.