Your physical address is the address where you live. Generally, all permanent residents should have a U.S. address. Exceptions may include permanent residents in commuter status or a lawful permanent resident converting to commuter status. In these rare cases, the applicant would have a foreign address near a U.S. border.
Your mailing address is where you prefer to receive mail. If your mailing address is different than your physical address, list your complete mailing address in the spaces provided. You may list a valid residence, APO, C/O, or commercial address in the United States. This may be a Post Office address (P.O. Box) if that is how you receive your mail. If your mail will be sent to someone other than yourself, you should include an “In Care of Name” as a part of your mailing address.
Again, most applicants should have a U.S. address. USCIS will not mail a new green card to a foreign address. If you list a foreign address because you are a commuter, your green card will be sent to the applicable port-of-entry.