I think it is somewhat of both. In your case, you chose to deploy it on server - but your architecture allows it to be deployed to several servers: the web components could go to web server, and EJB components could live on a application server. Usually, in J2EE application, you would also access database, which can live in its own server box, right? So, in classical J2EE architecture you have 3 tiers, even when you choose to collapse some of them for the time being.
Hope that helps,