Compiz And Beryl

What is the difference between the two? What are the features, advantages and disadvantages of these window managers?

not much. beryl is a fork of compiz so they use the same code. the main differences are that beryl has some more effects, settings, and options on how it works and stuff.

Which do you recommend? And more exactly what are those extra effects?

For me compiz works better.

Compiz is more stable, faster and smoother. Beryl has a lot of extra effects, like transparent cube.