Very interesting take and slightly different from the commonly understood definition of the two. I think the traditional definition describes one as outgoing, the other as shy. This seems to define it more as drawing strength from surroundings in one and drawing strength from self in the other, if I am reading it right.
I considered giving you my condensed version, which is that introverts absorb, and extroverts emit.
Of course, it's not just one or the other, but in general, introverts are sensitive to their surroundings, and extroverts tend to create an energetic atmosphere. It's an energy flow of sorts.