Q: Ways to explain/teach revert vs. update?

[Brian de Alwis]

On 18-May-2011, at 2:53 PM, Martin Pool wrote:
> bzr revert resets the working files to the given revision, which
> defaults to being the basis revision of the tree.  It never changes
> the basis revision, and it throws away your local changes.
> 
> bzr update merges your uncommitted changes (relative to the current
> basis) with the target revision, and writes the result into the
> working files.  It then sets the basis to the target revision.

And 'pull —overwrite' is like a revert but also sets the basis revision of the tree.  

Is 'update' different from 'uncommit' if update also sets the basis to the target revision?