Why do you need a visitor, if you can without him?

Question

Design patterns

Actually, why do you need the opportunity to do client.accept(visitor)when you can do it visitor.visit(client)?

Answer 1

Because in strongly typed languages, you would first have to cast to a specific type in order to call the visitor's method. Actually, for the sake of solving this problem, the template was invented. This is also known as "double dispatching".
Can you be more specific?