Difference between paid for advertising and editorial content in a newpapers?

An editorial is an opinion article written by a staff writer of the newspaper. An advertorial is a paid advertisement in article form that endorses a product or business. For example, a newspaper could print an editorial criticizing Obama's economic policies and also print a advertorial claiming that Dr. Jones is the best local dentist for children. Because they are paid advertisements, advertorials are subject to bias and favoritism.