John,
The biggest difference is how each app allows you to control the motion of the objects in your scene. Invigorator is keyframe based and has limits on the number of object containers called sets, which can be an issue if you’re trying to move lots of objects on an individual basis.
ProAnimator is much more powerful in how it allows you to create complex movement of large numbers of objects. Because it does not use keyframes, gives immediate feedback on the changes you make, and most of the hard stuff is hidden “under the hood,” lots of people find that ProAnimator encourages experimentation in a way Invigorator does not. One other huge difference – ProAnimator can be used as a stand-alone. Invigorator cannot.
On the other hand, Invigorator does give you very direct and precise control of the object containers called sets. For certain kinds of animation, this can be an advantage.
Both tools share modeling and texturing features.
If you wish, ask a more specific question and we’ll try to help.
Jon