I think this might help you in resolving your confusion
There are two main use cases of WEB in the industry
- Business to Consumer(B2C) : Whenever there is consumer directly
interacting with the business for its needs we always uses a
Web-Application to provide a communication between two parties.
- Business to Business(B2B) : It means one part of the business need
some input/services from another part of the business. Always a
Web-Service is used to meet the business to business requirements.
Usually a consumer never interact with the Web-Services directly we
only interacts with a Web-Application and a Web-Application interact
with a Web-Services for information/data or processing.
Taken from http://coder2design.com/java-interview-questions/