Each female is most probably a little more submissive or dominant in the bed. You verily find out for sure you may never know which one it is if she's just striving to please you. Once you detect which side of the line she falls on you can use that to your advantage and start pleasing her by playing into her desires. She will be more relaxed and at ease knowing you have received her for whatever she needs or wants to do in the bed to obtain the most out of it.
The most dominant female will like to have control in the bed. You may be more loath to give up all control if you have no hint that it would truly turn her on. She may not need to look like an insane guy who needs to hold you down and have sex her way and even though she probably would not look insane in your eyes she may image you seeing her coming on to powerful in her own head. On the other hand, if she is submissive in the bed you may not be as rampant as she would really like, but it may be difficult for her to say you that.