Initially, Ralph is described as "the fair boy" and Piggy is described as the "fat boy." "Fair" does refer to the lightness of his hair, but the word also means just, beautiful, and honest. These descriptions work out to be true. Piggy is fat, wears glasses, can't swim, and has asthma: all three are mild but real physical handicaps. These descriptions are accurate and the other boys will focus on these traits much more than they will on Piggy's mental abilities. Ralph is described as having the potential to be a boxer, so his athleticism is noted. In terms of physicality, Ralph and Piggy are opposites.
In terms of mental ability, Ralph is a confident, natural leader and Piggy is awkward but intelligent and a decent organizer. Piggy is the first to insist on having a meeting and decides to call the others with the conch.
As "fair" (just) as Ralph is, even he does not ask for Piggy's real name. However, they are the two most sensible, older boys on the island.
As was mentioned in the previous post, the most notable difference between Ralph and Piggy is their physiques. Ralph is tall, slim, and athletic. He is good-looking and described as being a "fair boy." In contrast, Piggy is shorter than Ralph and visibly overweight. Piggy also suffers from asthma and has to wear glasses. In addition, Ralph is confident and more reserved than Piggy. Piggy is a follower who admires Ralph and wishes to gain his friendship. Despite Piggy's multiple attempts to engage in a conversation with Ralph, Ralph dismisses Piggy and attempts to ignore him in Chapter 1. Piggy is also more intelligent than Ralph. He correctly identifies the conch in the lagoon and explains to Ralph the proper way to blow into the shell. The other boys on the island also admire Ralph and choose him as their leader. In contrast, they ridicule Piggy because of his appearance.