I sadly don't use either.. I have trouble getting anyone ever to actually click anything lol, i can't even get people to use the ReTweet buttons on my websites, let alone work out how people make money from social networks.
I love facebook, it is user friendly with many interesting features. Twitter is for people who have loads to write and quite boring!
Twitter is much better for driving traffic. However, for decent networking and conversions - Facebook is much better.
Twitter is better for targeted traffic. If someone is sick and writes about it you can send an actual affiliate link to a product and there's a chance to buy it from you.