Nya and Salva. How are these characters alike? How are they different?

A similarity between Salva and Nya is that they both struggle in the same country and worry about their loved ones being alive or dead. Salva had much harder childhood. He was displaced from his family and had to cross deserts, dangerous refugee camps, rebel soldiers.....In the end, both their paths cross with Salva helping Nya and her village access clean water.