What is the difference between slavery then and now?

Slavery then was mainly whites people against coloured people where the slaves used to do all the work on the farm and get treated like cattle, slavery now is different with machinery doing all the work, but still exists in some way in third world countries its the worst with children being bought and sold as slaves sometimes for sexual pleasure, it is against the law in countries to treat or keep someone against their will as a slave and usually if caught it carries a long prison sentence, but that does not stop some people from trying.