What is the fundamental difference between Factory Method and Abstract Factory?

Short answer

Factory Method uses inheritance to create one kind of object through a dedicated method, while Abstract Factory uses composition to create whole families of related objects without specifying their concrete classes.

Explanation

With Factory Method, a class has a createProduct() method that lets derived classes choose the concrete product. Abstract Factory provides a full interface with several creation methods for a compatible family of products, such as a GUIFactory interface that creates Buttons and Checkboxes for different systems (WindowsFactory and MacFactory).

Code example

interface GUIFactory {
  createButton(): Button;
  createCheckbox(): Checkbox;
}
class WinFactory implements GUIFactory {
  createButton() { return new WinButton(); }
  createCheckbox() { return new WinCheckbox(); }
}

Common mistakes

• Calling any static method that creates an object (such as User.create()) an Abstract Factory; a simple static creation method is called a Simple Factory.

Follow-up questions

• Why is the Singleton pattern considered an anti-pattern in most modern enterprise applications?

Sources

• Abstract Factory Pattern - Refactoring Guru