Advance parole is issued to an alien who is applying for, but does not yet have, permanent resident status. A re-entry permit, on the other hand, is issued to a permanent resident of the U.S.
On its face; an Advance Parole document is a piece of paper with the holder's photo on it, whereas a Re-entry Permit looks similar to a passport. An Advance Parole document functions like a visa to the U.S. while a Re-entry Permit functions, occasionally, like a passport.
In other words, an alien with an Advance Parole document still needs a foreign passport to enter the U.S, while a permanent resident with a Re-entry 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 Re-entry Permit is valid for two years.
(Updated 10/10/12 by NT)
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