Decorator and Builder.

Adapter.

Bridge.

Factory Method.

Factory Method is more abstract than Abstract Factory.

They are identical in purpose.

Abstract Factory is always static, Factory Method is dynamic.

Abstract Factory creates families of related objects, Factory Method creates one.

Bridge + Abstract Factory (to create implementation families and decouple abstraction).

Factory Method + Observer.

Builder + Adapter. 

None

By using reflection for instantiation.

By ensuring all products come from the same factory family.

By caching object references.

By enforcing Singleton pattern.

Increases complexity by requiring additional abstraction layers.

Prevents extensibility.

Forces tight coupling.

Makes client dependent on concrete classes.

To dynamically load classes at runtime.

To allow multiple inheritance.

To reduce memory usage by reusing builder objects.

To enforce immutability in the outer class by only exposing builder methods.

GUI libraries supporting multiple platforms (Windows, macOS, Linux).

Wrapping incompatible interfaces.

Creating a complex immutable object.

Separating interface from implementation.

Converting one interface to another the client expects.

Creating complex objects step by step.

Encapsulating product creation.

Separating interface from implementation.

java.lang.Runtime#getRuntime()

java.io.FileInputStream

java.util.Collections#singletonList()

java.util.Arrays#asList()

Creates product families.

Extends the abstraction and adds specialized behavior.

Converts one interface to another.

Implements the low-level platform details.