Essentially, they are both the same club.  I have played both 909 and 906 fairway woods in the past, and do not see much of a difference.  I was able to control the ball off the tee and the ground slightly better with the 906's, but then again, it might have been because I was more used to the clubs.  I will say what I say to all people who want club advice.  Go to a demo day, and try the clubs out.  In the end, it really isn't distance, it's more personal preference than anything.

Good luck!