WebsiteContains only static content or the information which end-user can read. all end-users can have same information to dispaly.
Web ApplicationUser and do intraction or any action are the web application. i.e. use can view,add,update and delete information based on requirement. also it’s by end-users, each user have their own data and they can manage it.
Please refer to the following link to know the differences between Website and Web Application,http://onlydifferencefaqs.blogspot.in/2012/07/aspnet-difference-faqs-2.html
Every website is a web application. but every web application might not be a web site. it might be a web based product etc.