Difference In Website And Web App

Web Application: A web application is a piece of software that can be accessed by the browser. A Browser is an application that is used to browse the internet. 
Web application needs authentication. The web application uses a combination of server-side scripts and client-side scripts to present information. It requires a server to manage requests from the users. 

Example: Google Apps, Amazon, YouTube

Website: A website is a collection of related web pages that contains images, text, audio, video, etc. It can consist of one page, two pages, and n number of pages. 
A website provides visual and text content that users can view and read. 
To view a website requires a browser(Chrome, Firefox). There are many types of websites like Archive websites, Blog, Community websites, etc.

Example: a restaurant’s web page where you can view the menu, hours of operation, etc. Or, a forum or blog.