Actually, it's rather simple. VuePro4 is becoming Vue Infinite with the addition of the Vue 5 lighting engine and some other significant features that will not be available in the Esprit line. Pro Studio is the name for a fully packed out Esprit 5 (none of the new modules are -needed- in VuePro, as it already has almost all of that functionality). The best price point upgrade path is from VuePro4 to Vue Infinite ($149).