What is the difference between a Passport Book and Passport Card ?

The passport book is something that you are going to show to the immigration when you are going to travel internationally. There are some countries wherein you will not be required to show a visa. All you need is your passport book, and you will be allowed to leave the country. The passport card cannot be used to travel internationally.

This is something that you have to prove that you have a passport, but you cannot show this to the immigration officers when you want to travel to another country. You still need to have your original passport book. The passport card can only be used when you want to travel from border to border.