Google 'AdWords' is the name for Google's Pay-Per-Click Advertising Program

• Organic Listing - is the name for the free listings (not sponsored or paid for). also called Natural Listings. The free listings appear along the left side of the search engine results underneath the top sponsored links. The web sites that appear in the free natural listing section have the most relevant content for a person's searching term based on the search engines interpretation.  There are only 10 web sites listied per page in the natural listing section.
• Pay-Per-Click Ads - are sponsored listing where advertisers  bid a set amount for specific keyword phrases. Everytime someone clicks on the sponsor's text link ad the sponsor's credit card is charged the bid amount, or close to that amonut, until the advertiser's pre-set daily budget is met. Pay-per-click ads (PPC) appear at the top of the search results page and all along the right side. The exact sponsor ads that appear are based on what the user's types in the search textbox. The relevancy of the keywords the advertiser bid on along with the dollar amount the advertiser bid helps determine the order in which each sponsor's text ad will appear. Also, with Google the more times a sponsor's ad is clicked on the ad may also get boost in placement without bidding a higher amount. That helps keep the most popular sponsored ads near the top.