Difference between web services and web application

Question

Lets have an example scenario:

Client opens a web site and finds the sum of two numbers which he enters from the textboxes.Then clicks on the ADD button.Two parameters a

Answer 1

A person drives a car. That car could be powered by an internal combustion engine, electric motor, or nuclear reactor. The power source doesn't matter to the driver though, as all they need to see are the controls and the road ahead.

The application is the car. Web services are the nuclear reactor.