Two of S.E. Hinton's most central themes to the novel are stereotyping and prejudice, so it is fitting that she purposefully divides the characters into two main camps: the Greasers and the Socs.
This division between the characters sets up the premise for the entire novel. The disparities between these two groups is more about social class than hair or clothing preferences. The Greasers have a prejudiced view of the Socs, thinking that they must have it made to have so much money to be able to drive nice cars and throw beer blasts down by the river; conversely, the Socs despise the Greasers for their seemingly dirty appearances and low morals.
Hinton ultimately uses the stereotypical gangs with their hatred and prejudice in The Outsiders to challenge those same stereotypes; in the end, Ponyboy learns to look past exteriors and see people as individuals.