In the end Lebron will have a better individual career than Bird. One reason will be longevity, the other will be competition.
But lets be real here, Bird was the better passer, rebounder, and shooter, by far, and what is often ignored, Bird literally had no holes in his offense game. He could score from the post, mid range, either wing, either corner, 3 pt range, facing up, back to the basket, off the dribble, off the pass, left handed, right handed. I mean, literally this guy could score from anywhere. If you take away Lebron's ability to barrel to the basket, this conversation is totally different, he's a rich man's Scottie Pippen.
Oh, and when Lebron can put up an entire season averaging 30pts, 10boards, 6 assist while shooting 50/40/90 (while only putting up 3 3's a game) then we'll talk. Oh, and the season before bird shot the same with 28.7 pts, 10 boards, and 7.6 assists with the same shooting percentages and shooting even less 3s.
Oh, all of this was with hand checking and hard fouls allowed.
In my opinion, there is no comparison of who is the better small forward. But Lebron will have the better career, and maybe even win more titles.