Ponyboy Curtis and Johnny Cade are the two main characters of S. E. Hinton's novel, The Outsiders. Although the boys are gang members, they are both introspective and quiet. Each of them comes from dysfunctional families: Pony's parents were killed in a car crash and lives with brothers Darry and Sodapop without normal adult supervision. Johnny's parents fight all of the time, and he has been the target of his father's rage and beatings. Johnny has also been severely beaten by the Socs, and he still carries the scars--and a knife--as a reminder. Both of the boys yearn for a better life, and Pony's love of school is one way he hopes to eventually better himself. Johnny's future appears more bleak; he is not a great student and his parents show little interest in him.
Ponyboy is an interesting character, in many ways because his emergence at the end of the story as a quietly confident young man has more to do with him figuring out who he really is than being toughened up through his rough interactions, the more commonly written technique for someone's growth. One of the reasons he is such an interesting character is that the interactions as part of the gang are really a sideline to his personal development, not the main story.
Johnny, on the other hand, is a character whose manner and actions are determined almost entirely by his interactions with and particularly the beating he received at the hands of the Socs. Johnny has an understanding of some of the things that Ponyboy feels but that understanding is the result of externalities rather than internalities.
This would be easier to answer if you could be more specific. There are all sorts of personal things about them throughout the book.
I guess the basic information about the two is that they are the youngest and smallest members of the Greaser gang. Pony is 14 and Johnny is 16. Johnny is also rather small, physically. Johnny has black hair and big black eyes. He is the "pet" of the gang -- they feel sorry for him because of his home life.
Pony has light brown hair that is almost red and grayish-green eyes. He is probably the smartest one of the gang. He's a good student and a good track athlete.