Rackets with the same weight could have different weight balance. A head heavy balance means the weight is shifted towards the head while a head light balance means the weight is shifted less towards the head (towards the grip). Any racket with a balance point of 285-290mm (length measured from the bottom of the racket handle, without any replacement grip being applied) is considered a balanced racket, while anything lesser than that is considered head light, and anything more is considered head heavy. See illustration at right.
The illustration at right is to just to show how is the weight balance point being measured. Bear in mind that actual balance point is measured WITHOUT string or also add-on/replacement grip being applied.
A head heavy racket will give you more power due to the momentum generated from the heavier racket head, but less maneuverability.
A head light racket will give you more maneuverability, but less power.
Do remember that once you string your racket and apply replacement grip to it, the original weight balance point will be shifted. Some players stick a kind of weighted tape called lead tape (the tape is made of lead) onto the racket head or anywhere closer to the racket handle to shift the balance point to their liking. This is a cheaper way in getting a ‘fresh’ newly balanced racket, as compared to buying a new one.
As a general rule, if you like to smash a lot and do not mind sacrificing a certain extent of maneuverability, get a head heavy racket for more power. If you play more defensive, fast or controlled type of shots, get a balanced or head light racket for better maneuverability. For starter, always get a balanced racket to be on the safe side, rather than committing to a head-heavy or head-light bias and later find that it’s not suitable for you. Once you know your characteristics of play, you can always replace your racket with a more suitable one later.