There might be some objects common to all parts of the program, and we require a single instance of it. The Singleton is a creational design pattern that ensures that a class has only one instance throughout the application. This instance is accessible from any part of the application with global access.

The Builder is a creational design pattern that allows us to follow a step-by-step process to construct a complex object. Builder design pattern separates the construction of the complex object from its representation by which the same process can create different representations (types) of the complex object.