50% less major wins. Not 100% on this but I think Tiger had around 40 tour wins as well. Rory 4 majors and less than 20 tour wins. To me that equals not even close.
Tiger had won 29 tournaments by the end of his 25th year, which of course is amazing. I'm not sure if anyone else will ever have a run like that, especially considering the level of competition.
But as Doomsday pointed out, Rory would be the favorite next year at Augusta, (which would give him 5), and he won't turn 26 until May.
Obviously, this is all conjecture, and we can't anticipate life's variables, but it does appear that Rory's swing and game are meant to last, and so far he's had the kind of dominating start that nobody but Tiger has ever had.
OTOH, Tiger may be done -- his era almost surely is.