Cherry says that what really separates the Socs and greasers is that the Socs don’t feel, and the greasers feel too much.
When Ponyboy meets Cherry, he is surprised that they have so much to talk about. They are from two completely different social classes, and usually their too classes are just fighting each other. Pony remarks that there is a “basic sameness” to them, and comments that it might just be money that separates them.
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. (ch 3)
As they realize later, they see the same sunset. Pony and Cherry are both different from the rest of their class, because they think about these things when most of the others just hate each other and rumble, fighting almost out of boredom and with no real reason.
One fight leads to another, which leads to another, because when one does something, the other needs to act to avenge what was done. It is a vicious cycle of violence and class warfare, and not everyone wants to take part in it. Pony and Cherry don't.