At this stage of his career--40 games into his first season--Rudy has been much better than Ginobli, who had the added advantage of being 25 in his rookie year.
Here are some after 39 game numbers for each:
Games in double figures: Rudy 25-5
Game with five or more boards: Rudy 7-0
Overall shooting: Rudy .428, Ginobli .379
Three pointers: Rudy .392, Ginobli .234
Free throws: Rudy .901, Ginobli .743
Points per shot: Rudy 1.31, Ginobli 1.09
Ginobli did have 11 games with two or more steals, compared to seven two or more steal games for Rudy. That was the only statistical category in which Ginobli outperformed Rudy.
(Worth noting: Rudy appears to have improved as the season has progressed. He's shooting .467 this month, compared to .421 in November, and averaging almost an assist per game more. His rebounds are up slightly, too.)
Among other things, this comparison points out that great players rarely are even excellent players in the first half of their rookie season. Ginobli's numbers, in fact, were intolerable for anyone other than a rookie. But he also improved significantly in the second half of his rookie season, but still not enough to post better statistics for the full season than Rudy has for his first half.
He definitely looks like he could be very special.