Authlogic with nifty_authentication, why use both?

Authlogic seems to be defacto now for authentication, but I was wondering how it compares to nifty_authentication.

The nifty_authentication generator does make it easy to use it along with Authlogic (configure the gem, then script/generate nifty_authentication -authlogic, I believe), but I was wondering why one would want to use both. Nifty_authentication states, "This is similar to restful_authentication, but simpler." Well, isn't that goal of Authlogic as well? I'm sure they're two solutions to the same problem, but just wondered why I'd want to use Authlogic as well.

Nifty_authentication does generate a lot of the validations as well, so I see it's benefit, but why use Authlogic as well?

Nifty_authentication is a generator to generate the files needed to use authlogic in a rails app. Not to be confused with what the gem does. It takes the place of building the User, session and adds some helper methods. Run script/generate nifty_authentication --help to see what it does.