Appropriate reverse komi and expected score difference are related but not precisely the same. If both players play so as to maximize their score, then the expected score difference and correct reverse komi should be the same, but in an even game the stronger player will probably not try to win by as much as possible, particularly once they are already confident in victory, and may even try to make the gap as small as possible.
Related thread from when I was brainstorming how Lagrange Points would work:
EDIT: corrected Android having thought that “try” was “with”.