Figurative language is descriptive in nature. Instead of simply saying my stomach was hurting because I was hungry, a good author will write something like: My stomach cries for food. In fact, your author, Pelzer, DID write that on the very first page, first chapter.
Tone: the POV of the author and the emotional investment. What's his purpose in writing the work. In this one the intent most likely was to expose the prolific nature of man's inhumanity to man and the resilience of the human spirit.