3D Stroke Interface (in After Effects)
The basic functionality of 3D Stroke is similar to After Effects' Stroke plug-in. It renders strokes based on the path of one or more masks. The big difference is that 3D Stroke treats the strokes in a three-dimensional manner. They are actually volumetric strokes in space, rather than strokes on a flat surface. This property becomes even more apparent when setting down the internal opacity in the advanced group of the plug-in. There is also the possibility to bend the strokes around the Y-axis.

Since the plug-in works in 3D, it has been equipped with a camera, and After Effects users have the option of using their After Effects composition's active camera. It supplies view space Z-clipping planes that can be used to place an object inside another and enable basic intersections.

Other differences from After Effects' Stroke include the repeater options in 3D Stroke that allow repetition of the strokes with a 3D transformation for each instance. 3D Stroke also features transfer modes, which are useful when stacking many instances of the plug-in in a single layer.

Previous Updates
Version 2.0 introduced tapering, where the width of the stroke can taper off at the ends. Another feature added in 2.0 is the loopable offset that makes it easy to move the strokes along their paths. Furthermore, the Bend feature has been extended with a Bend Axis control, so it is no longer limited to the Y-axis. Lastly, a Fade Start control in the Camera group had been added so the strokes can fade out into the distance.
The full 3D Stroke Interface is shown below, as hosted in Adobe After Effects.