What are the pros and cons of choosing to use active participation rather than passive participation in rental property?

All the questions and answers I've seen so far tend to push toward the active participation although I've read one that says something about not being able to deduct losses till property is sold.  I know I'm simplifying here, but I would really like to know what the thoughts are behind the decision to take the  active participation status or remain passive (of course, assuming we have the choice).  Thanks much for any explanation.