A submissive top is a top that likes it when the bottom is in control. Dominant bottoms can be just as powerful as dominant tops. The bottom prioritizes what they want over what the top wants. This can look like the dominant bottom pinning his submissive top down while riding him.
Disclaimer: Top does not = Dominant, and Bottom does not = Submissive. The top is the
person that penetrates, and the bottom is the
person that gets penetrated. The dominant is the
person who is in control, and the submissive is the person that submits.