Are there any differences to a heavier head racket and a lighter head racket? Are there any differences to a flexible and not so flexible racket? how do they affect your play?
Reading this article from Kwun will be a good start http://www.badmintoncentral.com/forums/showthread.php?t=21851
please search around the forums, the answers are there. head heavy allows you to flex the shaft of the racquet easier = more power but slower on defence. headlight = quick defence since theres no load at the head but has less power.