Yes it is. I will example myself so its easier to see:
Will Power: You and I both know I have very strong will power, except for some guilty pleasures. I have had strong will power ever since I can remember
Force of Will: Extremely inconsistant, would rather never enforce my will, except defensively. You are very similar in this regard, which makes trust easier for someone like me.
These are two very different self-concepts of a person.