Leadership: Both Katniss and Ralph find themselves in the archetypal position of the reluctant hero. Neither of them are very eager to become leaders. Katniss is overwhelmed by the adoration she receives after volunteering to become a tribute in her sisters’ place, and Ralph only agrees to be the leader of the original group when the boys take a vote. Both protagonists become a kind of moral compass for the book and are foils for those who pursue power at the cost of others. Jack desires the leadership position and takes it through violence, just as the career tributes attempt to do in The Hunger Games.

Personality: Ralph and Katniss share a soft spot for “the least of these” and become natural protectors of individuals who are shunned by the rest of the group. Ralph finds Piggy tagging along at every opportunity; Katniss pairs up with the young Rue as they navigate the arena. In both cases, this paternal protection does not extend far enough, and both followers meet their end. While this moment is a catalyst for Katniss’s righteous anger toward the Careers and the Capitol, Piggy’s death is merely a shock to Ralph that sends him running for his own safety.

Survival Skills: The primary difference between the two protagonists is their lack of preparation. Ralph and his compatriots are not even aware of what they should and should not eat on the island, as there’s evidence to suggest that the boys have diarrhea from consuming the local flora. Katniss has spent her youth in the forest, hunting wild game to feed her family, and her knowledge gives her an edge on her enemies. While the boys in Lord of the Flies seem to be stumbling their way through survival, ill-equipped characters are in the minority in The Hunger Games.

*This question has been edited down to a single question (per eNotes policy).

The Hunger Games and Lord of the Flies share many similarites as well as a fair share of differences:

Katniss and Ralph share many similarities as both characters are thrust into violent circumstances beyond their control; both characters find themselves isolated in a wilderness with other children.  The island in Lord of the Flies and the arena in The Hunger Games leave the children exposed to harsh deadly elements, where they must fend for their own survival.  Both Ralph and Katniss struggle with the elements of nature as much as they do the psychological trauma of the situation.  One major difference between Katniss and Ralph is that Katniss is much better equipped to hunt and kill than Ralph or even Jack. 

The Hunger Games and Lord of the Flies both explore the themes of violence and man's innate capacity for evil.  While the boys gradually turn savage on the island, in the Hunger Games, Katniss must defend herself against children who competitively seek her death.  Many comparisons could be made between the vicious 'Career' tributes who enjoy the thrill of the kill and Jack and Roger from Lord of the Flies who also learn to enjoy the power derived from violence.