Two auto-complete plugins?

Two auto-complete plugins?

I'm trying to use the autocomplete plugin, and I'm not sure how.

I'm confused by the documentation.  I found both of these through Google searches, but they don't list the same options, and I'm not sure what the difference is.

http://docs.jquery.com/Plugins/Autocomplete/autocomplete
http://docs.jquery.com/Plugins/AutoComplete/autocomplete

I'd like to have a form input that forces the user to pick one of the results that come back from an AJAX call based on the partial term they enter in the input.

Thanks!