In The Outsiders by S. E. Hinton, who are the Socs? Who are the Greasers? What does Cherry explain to Ponyboy as the difference between the Socs and Greasers?

The Socs and the Greasers are two different gangs in S. E. Hinton's The Outsiders.  
Early in the novel, Ponyboy thinks that the Greasers and Socs are nothing alike.  On the surface of things, a reader would tend to agree with Ponyboy, too.  A difference between the Greasers and the Socs is their socioeconomic status.  The Greasers are all poor teenagers, and they are coming from poor families.  In addition to being poor, most of the Greasers are from broken or abusive families.  Johnny's father beats him.  Ponyboy and his brothers do not even have parents around anymore.  On the other hand, the Socs are from the rich side of town.  Their parents are wealthy; therefore, the Socs have all of the fancy clothes.  Some of the Socs even have cars. Ponyboy absolutely believes that the main difference between the Greasers and the Socs is financial.

I really couldn't see what Socs would have to sweat about--- good grades, good cars, good girls, madras and Mustangs and Corvairs--- Man, I thought, if I had worries like that I'd consider myself lucky.  

During Chapters Two and Three, Cherry explains to Ponyboy that he is wrong.  Cherry correctly identifies that the main difference between Greasers and Socs is how each group feels.  Specifically, the Socs don't feel anything and the Greasers feel too much.  Cherry elaborates by explaining that in order to maintain a constant state of cool aloofness, the Socs are forced to be emotionless voids.  This emotionlessness can be contrasted with the Greasers, who are typically hot tempered and react to every little emotion that they feel.  

I thought maybe it was money that separated us.
"No," Cherry said slowly when I said this. "It's not just money. Part of it is, but not all. You greasers have a different set of values. You're more emotional. We're sophisticated--cool to the point of not feeling anything. Nothing is real with us. . ."
"That's why we're separated," I said. "It's not money, it's feeling--you don't feel anything and we feel too violently."