Marketing: The systematic planning,implementation and control of a mix of business activites intended to bring together buyers and sellers for the mutually advantageous exchange or ttansfer of products.
After reading both of the definitions it is easy to understand how the difference can be confusing to the point that people think of them as one-in-the same, so lets break it down a bit.
Advertising is a single component of the marketing process. it's the part that involves getting the word out concerning your business