In the context of divorce, Pennsylvania is an equitable NOT community property state. Whereas, courts in community property states attempt to distribute things 50/50 to the best of their ability, courts in equitable distribution states are not similarly constrained. The courts are more concerned with doing what is fair and 50/50 is not always fair.
When dividing the marital estate (assets acquired during the marriage) different facts in each case will determine how much each spouse gets—i.e. length of the marriage, the age and health of the parties, the economic circumstances of each person at the time the division of the assets will go into effect, etc.
In some cases 50/50 is in fact fair. However, in some cases 70/30 in one spouses favor is fair. The factors listed above and many more determine what is fair in each case. Additionally, these factors may allow for each asset to be divided a different percentage. This means while equity in the house may be divided 50/50, the retirement accounts may be divided 46/54.
Parties can either reach an agreement as to how the estate should be divided or, at the requests of the parties, the courts can determine how assets should be divided.
This may seem like a lot, but determining how to divide the marital estate is only one piece of the puzzle. Equally important is determining what actually is marital and eligible for distribution.