What I remember about the both of these players at such a young age is that at 23 Lebron James had already been considered a physical freak of nature that was mature well beyond his years in both his physical presence and his his depth of understanding for the game. Michael Jordan was a freak of talent who's body was still maturing and changing into the body of a man and who's understanding of the game had yet to reach it's full potential.
LeBron has been so good to this point due to the extreme maturatation process that had taken place in his body, in his mind, and in his game. Michael had been so good to that point because he had such immense talent and such great teaching and coaching to that point.
Michael had already won an NCAA Championship at North Carolina University at the tender age of 19 and had done so by hitting a game winning shot in the Championship game against another team that had a future NBA Hall of Famer on it. Michael's pedigree in a time where college stars stayed in college until 22 was firmly cemented. The NCAA had deeper more talented teams back then as did the NBA.
It is near impossible to compare players and teams of different eras but it is especially difficult to draw comparisons of anyone to Michael especially at distinct ages. Michael's talent was visible and present from the outset but his body and mind still had to grow before his ultimate success would come. I'm not sure the same can really be said about LeBron because the first thing people noticed about the man, even in high school, was that his body and mind were those of a man among boys at such an early age.
So in closing at 23, I'm sure I haven't seen the best of LeBron but I don't see his game getting that much better than it is now. I see his teams improving significantly but probably not LeBron's game. The same could not be said of Jordan. At 23 you could still see that Michael hadn't come close to reaching his full potential. He still had so much more to learn and to grow individually Michael's game would improve both individually as well as collectively with a team. I am not sure I can make the same claim about LeBron..