Originally Answered: If a girl who is 13-14 has another girl whos 8-9 do sexual things to her does that make is rape or molestation
Molestation/rape is not just about age and the law. It's about the impact it has on those involved and the way the victim precieves the events. I would say that the girl you described was molested, based on your information. There is a big emotional/mental difference between two kids who are 14 and 9 than there is between two who are say, 25 and 20. Five years difference in children is a BIG difference.
The fact that your friend says it was "fun" makes no difference. Many victims of sexual abuse report that at the time it "felt good", something that unfortunately leads to a lot of guilt and shame on the part of the victim. Children often have involuntary physical reactions that lead to a lot of confusion. They think that they asked for it or that they were responsible for what happened. This is not the case.
I also find myself wondering about possible trauma to the older girl. The statement about playing "mommy and daddy" implies to me that she has probably seen her parents engaging in sex acts. It's possible that it was a one-time, accidental thing, but the fact that she was coercing another, younger child into sexual contact makes me wonder if she has experienced sexual trauma, herself.
Your friend is obviously still thinking about this. Does she feel guilty, angry, sickened, or afraid about it? Does she have intrusive thoguhts (thoughts about what happened that won't go away), nightmares, or flashbacks? I'm sure she's confused and embarassed, but It's a sign of what a good friend you are that she feels safe enough to share this part of her history with you. Let her know that you care, that you won't judge, and that you will support her in whatever she chooses to do about it. Let her know that she is not responsible for the way she responded to it at the time - she was just a kid. (It might help to have her think of a kid she knows who is about 8-9, and ask her is she would hold that same girl responsible if she were in the same position. It's a good technique for getting perspective. We often apply our adult reasoning to our child-selves, but it's important to remember the difference.) This really is about her perception of what happened, and you need to let her know that. Say "If you feel as though you were hurt by this, then it was wrong."
If you need more information, I suggest going to www.rainn.org
Good luck to you both