I think it comes down to the difference between ambition and drive. Ambition to me means the ability to utilize your energy efficiently towards a very specific goal (i.e. get more money, power, prestige, etc) while drive is the ability to utilize your energy efficiently. There may be a goal, an unclear goal, or no goal.
I think ambition, in the traditional sense, is limited to "employment type" goals where "if you do ___, then ____ will likely happen and ____ will be your reward."
Drive is something more broadly emcompassing, and yet harder to have. It's the ability to do those things you have to do towards your goals, but with no guarantee, or even perhaps a very poor likelihood, of reaching your goal.
One who is extremely ambitious, but lacks internal personal motivation (drive), can only ever work up someone else's ladder. If they do it successfully maybe they'll be an upper manager after 20 years and a VP after 30 years. But that's as good as it gets.
The kicker is, it's very difficult to identify even if you have personal drive when you're too focused on ambition and exhausted from your full time job every week.
FI allows you to relax and truly discover in yourself whether you have drive in the first place, and gives you time to culture and channel that drive.