Any gifts or inheritances received by an individual during the relationship which have not been dissipated will not be shared. Any assets owned prior to marriage will not be shared. Any assets covered by a marriage contract will not be shared and any personal injury payout for pain and suffering will usually not be shared.
There are many addition small exceptions which can apply to family property and result in the non-equal sharing of that property but those mentioned above are the most common and typically make up the largest sums which are considered during separations. It is integral to hire who is familiar with all of the exceptions to property division in order to protect your rights in this kind of situation.