jQuery takes a "sensible defaults" direction. Animations have default values. You can get sliders with one line. Everything works intuitively. YUI takes a "

jQuery takes a "sensible defaults" direction. Animations have default values. You can get sliders with one line. Everything works intuitively. YUI takes a "be explicit up front" direction. You want an animation? Tell us the timing, direction, and easing up front. Instantiate your animation. Run your animation. You want a slider? Tell us the min, max, length, and default values when you create it. jQuery works great when you want to be fast and done. YUI helps you if you want to be a little slower and get everything tweaked to your exact requirements from the start.