I saw that also, but I don't know how to tell the differences between the two. If you wanted the one with the higher horsepower it would be safer to go with a 2002 and newer model. Maybe you can call the dealer and give them the VIN, they should be able to tell you the engine it has. I'll do a bit more research to see if I can find out for you.
Now if we could get our hands on one of these engines we would kill, they are available on the 2003 and newer A6's I believe:
4.2TT 40v 4,172 cc (254.6 cu in) V8 2xDOHC 339 kW (461 PS; 455 bhp) @ 2,800 550 N·m (406 ft·lbf) @ 2,000 4.5 sec 168 mph (unlimited) 2003–2004