Originally Posted by Megadrum
What are the differences between a lo-fi and a hi-fi?
I don't really think of compressors like this - to me, these words are better suited for for describing a modulation effect or a synth than a compressor. I like to think of things in terms of "clean" or "distorted."
Clean is just that - clean. Good for a touch of gain reduction or thickening, probably on a vocal or a drum that just needs a bit more "oomph."
The waves RCompressor comes to mind here, as does the Sonnox offering. Think of these more as a "fattening" tool than an effect.
Dirty covers everything from a bit of grit all the way up to pure sonic mayhem. On the lighter end of this scale might be your hardware emulations - API, SSL, and the vintage stuff can all get quite dirty.
When I need insane compression for sound design or making a boring loop/drum recording sing, I go here: Audio Damage :: Rough Rider
Best of all, it's free