In the past many SEOs have called organic search results the results on the left side of the page and the pay-per-click / AdWords results as the results on the right side of the page. As Google has grown more aggressive witht promoting vertical/universal search I think a better way of defining the portions of the search result page are ABOVE THE FOLD and BELOW THE FOLD.
As recently as yesterday Google stripped the phone numbers off of non-sponsored map listings, even if you were doing a navigational search! And that shows that the primary goal of the maps is as filler content (rather than utility).
Update: it looks like Google claimed the phone number removal was a bug, but weird timing that the bug appeared at the same time they started selling premium local ads that appear on the regular search results.
So lets redefine these search result pieces as they are...
AdWords Ads: the ads at the top of the search results and those which run down the right rail of the search results.
Universal Search Results: filler stuff to put in the search results to a.) drive the o