Johnny and Dally are about as different as people can be while still belonging to the same gang. Dally is a tough guy who really does not care about anything. By contrast, Johnny is something of a delicate guy. He is very fragile. This is partly because of having been beaten so badly by the Socs. But it is also because of how bad his home life is.
So Johnny ends up being "everyone's pet" in the gang. The one they all look out for. Meanwhile, Dally is the meanest guy in the gang and one who takes special care to try to watch Johnny's back.
In the book "The Outsiders" Johnny has dark brown hair and brown eyes. He comes from a home where he is beaten and verbally abused. He is neglected. Johnny has no one but his friends to serve as his family. Johnny listens to people and seems to understand them. He is skittish and worries a lot. He scares easily. He is able to relate and win the love and support of Dallas.
Pony Boy is the baby of his family. He is being raised by his two older brothers who despite their differences do maintain a family relationship. He also has the protection of his brothers. He has dark blond hair and blue eyes. He is very intelligent and reads poetry. He is also able to write well and has the potential to go on to college.
Pony Boy has the advantage of being able to be rebellious because he has the support of Darry. Darry is the authority figure in his life since his parents died. Pony Boy also has nightmares about his parents death. He is not that fond of Dallas. He has more self-confidence than Johnny.