Basically everybody in the US uses the phrase "zip-code" informally to mean postal code even when talking about international addresses.
Say what? Where in the U.S. do you live? I've been all over, and I've never once heard them called 'postal codes'; always and every time 'zip codes.'
https://www.google.com/search?q=site:usps.com+"zip+code" returns 120k results
https://www.google.com/search?q=site:usps.com+"postal+code" returns 372 results