Mars has the same basic internal structure as the Earth and other terrestrial (rocky) planets. It is large enough to have pressures equivalent to those throughout the Earth's upper mantle, and it has a core with a similar fraction of its mass. This diagram shows the depths at which high pressures cause certain minerals to transform to higher-density crystal structures. In contrast, the pressure even near the center of the Moon barely reach that just below the Earth's crust and it has a tiny, almost negligible core. The size of Mars indicates that it must have undergone many of the same separation and crystallization processes that formed the Earth's crust and core during early planetary formation.
Illustration credit: JPL/NASA