Yes; it looks like it's more focused on a lightweight set of core features (obviously opinions as to what constitutes "core" features may vary).

It actually seems more reminiscent of early mootools.

Different,yes, but not necessarily in a way that matters to me.

They specifically refer to the basic JQuery UI elements when they state, under "Essential tools for modern websites"

<blockquote> Let's face it: do you really need drag-and-drop, resizables, selectables or sortable tables in your web applications? Websites are not desktop applications. They are different.

What you really need are tabs, tooltips, accordions, overlays, smooth navigation, great visual effects and all those "web 2.0" goodies that you have seen on your favourite websites.

This library contains six of the most useful JavaScript tools available for today's website. The beauty of this library is that all of these tools can be used together, extended, configured and styled. In the end, you can have hundreds of different widgets and new personal ways of using the library. </blockquote>

This looks like repackaging the more popular stand-alone jQuery plugins/widgets into a single bundle/distribution, with nice docs and demos, very different from jQuery UI which is more like half a framework and some widgets.

And I have to say that I agree with them. Whenever I am confronted with, say, a "window" in a web app (i.e. a popup that I can move around in the browser), it just feels weird.