In object oriented programming, classes and interfaces are two separate and distinct concepts. A class provides structure to create objects that have methods and attributes, while an interface is an abstract class that enables a class to adhere to a certain protocol.

Classes are used to store data and implement the logic related to the data. Classes can contain variables and methods, or functions that specify how a given data type behaves.

An interface is like a template which defines a group of related methods with empty bodies. The implementation of the methods is provided by the class that implements the interface. Interfaces are used to enforce a certain behavior in the class that implements it, as all methods defined by an interface must be implemented in the class.

Also, while a class can extend only one class, it can implement multiple interfaces. This is useful when unrelated classes need to share the same behavior.