Advance Parole is issued to an alien who does not have permanent resident status. A Reentry Permit is issued to a permanent resident of the U.S. The two documents are dissimilar in physical appearance: Advance Parole is a single piece of paper bearing the alien's photo, whereas a Re-entry Permit looks like a passport.
An Advance Parole functions like a visa to the U.S., while a Reentry Permit functions like a passport. In other words, an alien with an Advance Parole document still needs a foreign passport to enter into the U.S., while a permanent resident with a Reentry Permit does not need a foreign passport to enter the U.S. Another difference is the duration: Advance Parole is valid for one year, whereas a Reentry Permit is valid for two years.
(Updated 10/11/2012 by AD)
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