A passport card is valid for entry and exit by land or sea ports in the United States, Bermuda, the Caribbean, Mexico and Canada. A passport book is also valid for this type of travel, but the passport card, which can easily fit in a wallet, may be more convenient to carry.
Only a standard passport book--not a passport card--is valid for air travel outside the United States. This includes air travel to Canada, Mexico, Bermuda and the Caribbean.
Passport cards cost much less than passport books. In fact, a renewed passport card costs less than one fourth the price of a standard passport book.
The period of validity for adult passport cards and passport books is exactly the same. Both are valid for 10 years for persons 16 and older, while both are only valid for five years if you are under the age of 16.
