Applications are like what we use on mobiles....or destop application... where as Web application are used in browsers only...and with help of browsers only eg: Application: facebook app on Mobile web application: facebook used with the help of a browser!!!
Let me make it simple Web based application which can b accessible from anywhere in the world with internal Desktop application requires installation on yout Operating system
web application require internet connnection when it will run..but for desktop app..its just software. so dont require internet..we directly run