According to Britannica, Crepe is defined as the following:
Therefore, Crepes are one type of pancakes. Or, you can say its French way to cook pancakes. Different from normal pancakes (i.e. US style pancakes), Crepes are very thin and only use plain flour while the usual pancakes use self-raising flour or baking powder to make it fluffy and genereate bubbles.

The images below with the left being crepes and the right being pancakes.