What is the difference between marketing and advertising?

I am going to look at colleges over vacation and I think that my dream job would be something to do with fashion merchandising or being like a buyer. I am not sure what major would be the best for this. I am thinking either marketing or advertising/public relations. Which major would help me with those career goals and also offer me the most flexibility in finding other jobs?

Marketing/advertising/public relations to be successful mastering these three is a plus. Bottom line what touches the heart of the majority of people in a way that they wont forget.
psychology courses are great to learn people and there desires and what effect them in a positive or negative way.