Some already have said that the Pro 800 is the predecessor of the Tour 800. It has the same graphics but the name is different. If so then the pro may be really old as the Tour 800 came out more than 4 years ago (someone correct me if i'm wrong here). Someone told me once (someone wise and tells all truths) to buy the new stuff out there, don't buy old racquets especially if its going to be your primary weapon. The only exception is if you're going to add them to your collection.
The difference is that the PRO was made for Europe, It was only made once a few years ago. In terms of apperance and specs, they are identical. I have a Pro and a Tour, they are the same. Old racquets and new racquets, whats the difference, racquets dont go bad!! When the racquet is brand new, but was manufactured 3 years ago, its still just as good as one made yesterday. As long as it has not been strung and played with. So if any find great deals on older models that they like, go for it!!!!
It has nothing to do with going bad but has to do with availability. Its better to get use to a racquet that will have a good long market lifespan.