| Class and instance are distinct entities. | All objects can inherit from another object. |
| Define a class with a class definition; instantiate a class with constructor methods. | Define and create a set of objects with constructor functions. |
| Create a single object with the new operator. | Same. |
| Construct an object hierarchy by using class definitions to define subclasses of existing classes. | Construct an object hierarchy by assigning an object as the prototype associated with a constructor function. |
| Inherit properties by following the class chain. | Inherit properties by following the prototype chain. |
| Class definition specifies all properties of all instances of a class. Cannot add properties dynamically at run time. | Constructor function or prototype specifies an initial set of properties. Can add or remove properties dynamically to individual objects or to the entire set of objects. |