Before I begin, let me say that I love my children dearly. I love them differently, but dearly. They both have their own unique personalities with their own strengths and weaknesses and I'm learning to accept that.
With that said...
The ant and the grasshopper fable suits my boys well! I won't name names, but it's very clear that one is very task oriented. Though he is playful, he knows when to get down to business. He can be depended on to get finished or make progress without a dozen reminders and warnings. The other is very playful, always enjoying an opportunity to act out a scene with his action figures or sneak in a few minutes of reading from his comic books. Let's say he has a real zest for life. He needs to be reminded to do things he full well knows to do (repeatedly) and is rarely prepared. It's kind of funny to watch, because they're from the same environment. No matter how many times I fuss, nag, yell, praise, redirect, correct, it doesn't change.
The challenge for me as we progress into a new stage of parenting is to accept it. The whole nature vs. nurture argument is right here before my eyes. Their personalities have been nurtured to a certain extent, but at their core many aspects of their personalities are innate. While I can help them play up their strengths and work on improving areas of weakness, I am not God. They are who the are, and that's who they'll be.