these primarily deal with bindings, templating, etc. For RIA one needs complex even propagation. The difference in my mind is that RIA are much more like a workbench than a horizontal website. In a workbench you have toolbars, menus and panels which can be customized for the complex workflow. Typically such an application has only a couple of views but many possible actions, where as webapps have several views, but only limited number of actions directly affecting what is on the screen.