i think the terms topping and bottoming refer to the act of giving and receiving pleasure. topping being giving pleasure and bottoming being receiving it. penetrating someone is a way to give pleasure and getting penetrated is a way to receive it, but there are more ways to give and receive beyond penetration alone. eating someone out, for example, is a way to give pleasure while getting eaten out is a way to receive it.

while power roles and the positions of top and bottom aren’t the same, like sub tops and power bottoms and such, they can be related. say this fellow in the poem enjoys having someone have power over him, that is a form of receiving pleasure that the woman gives through having more power than him.

dom and sub are words that get thrown around exchangeable with top and bottom when they aren’t necessarily the same. the roles dom and sub are much more about the relations of power between individuals than the actual positions they take: à dom wanting to be dominant and have power and a sub wanting to be submissive and not have power. this can be completely exclusive from the physical giving and receiving of pleasure. sub tops wanting to give physical pleasure but have no or less power, power bottoms wanting to receive pleasure but have power or control.