[tor-relays] significance of different bandwidth values

Question:

What the difference between the bandwidth value given by

getinfo ns/name/xxxxx

...

...

w Bandwidth=297

and

getinfo dir/server/authority

...

...

bandwidth 300000 375000 335872

Here they are close, but sometimes they are far apart. The first above is what shows up in the Vidalia Network Map and the latter is less visible, but shows up in various web tools for monitoring the Tor Network.

In particular, how are these values used in choosing route paths?

Thanks