Each of your clubs is different: your 3I is longer than your wedge, and your driver has an entirely different shape than your 7I. Some may have graphite shafts, some may have different grips, and some may be made by different manufacturers.
One way to improve your play is to match the swingweights of your clubs to your swing and to each other. Clubs with different swing weights have a different "feel" to them. Swing weight is a measurement of how the weight is distributed in a club. The shaft, the weight of the head, and even the size of the grip can affect the swingweight of a club. The lighter your swingweight, the lighter the head of the club will feel.
About.com answers the question "what is swingweight?" but an important distinction is this: swing weight and overall static weight are not the same.