Difference between web clients and application clients

Hi all,

What is the difference between web clients(fat clients) and application clients(thin clients) ?

If you take 3 tier architecture

Browser (1st tier) <-----> webserver/webapplication (2nd tier) <----->
Application server/EJB application


Here browser is the web client/ thin client
And webser is the application client / think client

Application server is the service provide for application client