hello, I have max 4 and viz for. The only difference that i can see is in the toolset for animation and the radiosity. I really like viz since it had the rediosity built in an you can get really awesome results interior and exterior. Otherwise if you buy MAX and you want GI you need to buy extra plug-ins. On thing that VIZ does not do is caustic, but those can be faked if you really need them i guess. The GI in viz is also pretty fast compared to brazil(for max). I hope this helps. look at some of my work.
http://www.cgarchitect.com/gallery/g...earchChecked=1