The main advantages would be a better renderer (matter of opinion on my part), mainly I say this because some of the abilities that Vue's renderer is just getting, Carrara has had for awhile now, so its a bit more mature and stabalized on the rendering side of things. You can actually model objects for your scene's in Carrara, you have a spline modeler, vertex modeler, text modeler, metaball modeler, boolean modeling, and the Amapi 7 modeler. You also get a lot of special effects capabilities that Vue does not have. IE. Particle systems, particle fountains, etc. Personally while I like Vue a lot, and think its incredible at what it does, I think Carrara is a better choice for a more well rounded package with a broader range of features.