Chris Nolan's Presentation

After listening to Chris Nolan's presentation on searching the internet, I found the differences in search engine credibility to be quite interesting. I used to think that all search engines would pull up the same links to a certain topic; but, he claims that Google and Yahoo, for example, have different priorities and thus different links or sources. So, depending on the topic, Google might have better links to more credible websites, have a greater variety, or get straight to the desired topic for which one is looking compared to those of Yahoo. Now, when I search a topic on Google, I will compare the results with those from Yahoo or another search engine in order to get access to the best websites or closest to what I'm looking for.