Thanks very much to all who've responded.
i guess i'm most interested in the boundaries, where one thing starts to blur into another...i'm not sure i framed the question well

From Flaming_Redhead's post, it seems the association for top/bottom is with more public, casual play, as opposed to an ongoing relationship, for one thing. i'm not sure this fits in the strictest definition of the term(s), which i understand as merely denoting the active versus the passive player.

Another association i'm picking up (and please correct me if i'm wrong, Flaming_Redhead) is where the player's attention is focused...for a bottom, on herself, for a sub, on her Master.

So...more questions:
How about if the bottom is very much interested in the top's enjoyment - is she being a sub?
Is it only considered "submission" if you're doing something you don't like, in order to please Master or Mistress?

And, since i've been called a lot of things, but never "bedroom submissive," let me frame a different scenario: If i suggest a bottom choose five things she likes, and two she doesn't like at all, from her list...am i now Domming her?