"Alpha" refers to the stage of software code- Alphas go out to hard-core testers who know how to deal with technical issues and report bugs in a coherent way.  "Beta's" is what Vue ships out to its customers so that they can discover whats not working...and it will be fixed in next major release. heh!- (So Vue 6 bugs will be fixed in Vue 7...)... just kidding- sort of... (most Vue 6 bugs will be fixed by Vue 6.2 probably...)

Or- in the Terragen "Alpha"- you may be mis-understanding what they are saying- T2 uses billboards (which are like smart alpha planes) and "instances"- but also imports 3D model objects as well- like X-Frog plants. This is basically the same technology Vue uses in it's Eco-systems. Vue's in-house "Solid-Growth" plants however allow greater variations in EFX- and is of course E-on's main "ace card"- which is why Vue 6 will have an even MORE evolved plants and eco-system- which it of course needs to stay ahead of Terragen and Carrara in that area of EFX...

It sounds like there is no need to buy Terragen or Vue... just subscribe to Arizona Highways magazine- scan those pictures into your computer and post them in the Renderosity Gallery...