[tor-relays] significance of different bandwidth values

[starlight at binnacle.cx]

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