2 different scripts, both with a few advantages over each other.
Anyways, joe, I noticed you are a new member over there (I'll get your email fixed asap so you can sign in). Once signed in, you'll see some hidden forums - in the template forum are some "ubb.skin" templates for those who prefer the way ubb.classic looks. We have another set coming that are even closer in style to ubb.classic as well