Marketing is the general term for everything a company does to get the market to buy thier product/service. However, no company can simply go out and do "marketing". They have to do a functional part of marketing. This can include advertising, prospecting, or something along those lines. And you can take that even further. For example, prospecting could be done over the phone or face to face. Advertising could be done on a billboard, through direct mail, on television, etc.