This is an FAQ I recently wrote up on the difference between different types of lighting. I have seen these questions asked quite a bit so thought this would resolve some of those questions.
http://www.saltcreep.com/forums/faq.php?faq=reef_faq_lighting#faq_difference_between
http://www.saltcreep.com/forums/faq.php?faq=reef_faq_lighting#faq_difference_between
