Compass is a real stylesheet framework — not just a collection of classes. With Compass, you still use the best of breed css frameworks (blueprint, yui, 960); ported to Sass to make them easier to configure and apply to your semantic markup.
Compass is a CSS Meta-Framework that provides ports of the best of breed CSS frameworks to Sass and ready to use in your ruby-based web application or stand-alone via a simple command-line interface.