Both trilogies are seriously alike. A sixteen-year-old girl from an overlooked faction/district in a dystopian society gets put in a competition with a limited number of winners and high stakes. At the end of the book, she becomes a major part of the rebellion - which fills up the next two books. However, the undercurrents of these two books are extremely different.
Katniss Everdeen, the main character, is introduced as a sixteen-year-old hard working, family loving, tough girl who is determined to do her best to stay alive and keep her sister safe. When her sister Prim is reaped for the Hunger Games, Katniss volunteers the second she remembers she can. In the beginning, Katniss is characterized mainly by a will to live and that dying love for her sister, even scorning Gale's and Peeta's rebellious speeches.