In preparation for my Internet Librarian talks, I was playing around with Google, looking for how much my search results varied based on how I constructed my search. I was surprised to see how much they differed.
First, I tried searching carbon neutral winery and then searching winery carbon neutral. Not only were the results significantly different, the first search retrieved 93,500 results and the latter retrieved 195,000. (My hunch is that since there are plenty of sites that have the exact phrase "carbon neutral winery", Google delivered the results from a "shallower" search than for the less common wording of "winery carbon neutral".) I also found that, among the first 20 results of each search, there were five results that appeared in only one or the other search result.
My other surprise was the difference in results between standard results and limiting the search results to web sites updated in the last year, a technique I often use to get more relevant results. There was very little overlap between the two search results and, while I still prefer the results with the last-year filter, I am reminded that I could be missing some good material that way.