NASA releases color images of Pluto and Charon. The heart shape on Pluto is different colors indicating different geologic, tectonic, or morphological origins. The big red spot near Charon’s north polar region are most likely nitrogen particles from Pluto. The sun burns off the particles on the areas facing the sun, but not the polar region which faces away from the sun for decades.
Some regions are relatively ancient, and other places are very young and currently undergoing geologic evolution.