Direct answer
A U.S. passport book supports international travel by air, land, or sea. A passport card may be used to enter the United States at land border crossings and seaports of entry from Canada, Mexico, Bermuda, and some Caribbean destinations. It cannot be used for international air travel.
When the book is the safer choice
Choose the book if you may fly internationally, need visa pages, or want one document that covers the broadest international travel. Even when a planned cruise may accept a card, an unexpected need to fly home internationally requires a passport book.
When the card may fit
The wallet-sized card may fit travel limited to the Department of State’s approved land and sea routes. It can also serve as REAL ID-compliant identification for domestic air travel. That does not make it valid for an international flight.
You may hold both
You may apply for a book, a card, or both. An eligible adult who already has one may use the renewal route to request the other, subject to the current renewal conditions. Children under 16 must apply in person and cannot renew either document.
Validity and fees
The book and card have the same validity period: generally 10 years for applicants age 16 or older and 5 years for children under 16. Fees differ by document and application route. Use the current Department of State fee page or calculator before applying rather than relying on an amount saved elsewhere.
Check the destination too
A U.S. passport proves identity and nationality, but the destination controls its entry rules. Verify the destination’s current requirements and the carrier’s document rules before travel. A passport document does not guarantee admission to another country.
Official sources
- Department of State — Compare a Passport Card and Book
- Department of State — Passport Application Help