d200 has AF-S and AF-C focus priority, which means if u select focus priority in auto focus continous, it will only fire the shutter when it has focused, same goes to af-s, not sure if d80 has it.
3fps for sports is not fast enough in the d80, while the d200 5fps is almost just nice.
The motor in d200 is more powerful too, thus maybe a little faster af when using with non AF-S lenses.
i dont think the d80 would suit ur sports photography needs, unless the sports u cover is like golf...
the d200 simply has faster af and more fps. wad u need for ur sports shoots... as simple as that.