The term "lawful permanent residence" refers to a foreign national who has been given the right to remain in the United States permanently (subject to certain conditions). LPR status does not expire and as long as the foreign national LRP does not abandon it or misbehave (and get put into removal proceedings), LPR status does not need to be renewed.

On the other hand, when someone receives immigrant status on the basis of a marriage that is less than two years old at the time the status is granted, they are given what is known as "conditional residence." This simply means that they have all of the rights and privilages of permanent residents, but their status is not permanent. Instead, it is granted for a period of two years. In the 90 day period immediately prior to the end of the two year period, the conditional resident must apply to have the condition removed and have his/her status made permanent.

The purpose of this rule is to discourage people from evading the immigration laws by entering into sham marraiges to gain immigrant status