I've come across a number of things lately that have gotten me thinking about user interface versus user experience and how the distinction relates specifically to rich Internet applications. This isn't a new topic, and one Google search reveals a lot of history and commentary but as RIAs have gotten more attention, I think the difference between the two is even more important so we don't get caught up in arguments about richness.
Rich doesn't have to mean heavy. RIAs can still provide a lightweight user interface while using animation, transitions, and effects in a way that enhances the user experience.The richness aspect of RIAs seems to be the most controversial to people (discounting the 'I' debate) because most see richness as a requirement under which developers/designers will stuff gratuitous and heavy user interfaces. They have a history to be wary of. Flash is littered with bad examples of adding animation and any interactive tool out there will have its fair share of the same. But richness is about a lot of things. It is about a more sophisticated user interface, but it's also about being able to handle more data, being able to provide a valuable user experience and being able to incorporate video and media where appropriate.
That's why the UX vs UI issue is so important. When I think about good RIAs I think about the ones that have blended the two together to create both a rich and usable application. Rich doesn't have to mean heavy. RIAs can still provide a lightweight user interface while using animation, transitions, and effects in a way that enhances the user experience. As the traditional commentary notes, user experience is about much more than what's on the screen. It's about how all the pieces fit together. One of the reasons RIAs are so compelling is because we now have the tools and the technology to put those pieces together in powerful ways. The end result absolutely should not be a bloated user interface (though of course, we'll see mistakes made). In the end it should be about creating usable interfaces that tie back to a better overall user experience.