Question

I am not seeing any difference. Looks like both Patterns are trying to compose objects. Can anyone explain the intentions behind these two patterns?

Answer 1

They are different patterns, but they are often used together.

The point of composite is to apply the same operation to a bunch of elements that share an interface. The point of visitor is to extend a bunch of elements with a new operation without changing their implementation nor the caller’s implementation. Therefore you often see:

Composite c = new Composite();
Visitor v = new ConcreteVisitor();
c.visit(v);

This way you can keep the implementation of the composite and the classes that are in the composite static, and only vary the kind of Visitor you apply to them.