The Pro variant includes a few additional features in SketchUp (most notably Solid Tools, which are fancier or more convenient forms of the “Intersect With…” set of functions that are available in all versions of SketchUp). The Pro variant also includes two independent programs: Layout, which is for creating 2D documentation for models, and Style Builder, which builds styles that can then be used with SketchUp. For many users, I suspect that the inclusion of Layout is the major differentiating factor between Pro and non-Pro.
Pro would not make a difference to how extensions are install and maintained.
For what it’s worth, I use @Fredo6’s Animator plugin a lot (I’m using it now on a personal project). I access it via the Tools menu, Fredo6 Collection, Clip Editor (as you noted earlier in this topic). I have never attempted to uninstall it or to modify or remove toolbar items.