Every search engine has its own way to rank or categorize sites. Google uses the page rank method. Yahoo also uses a similar method but the name and parameters are different to rank any site in yahoo's search results. For example, yahoo gives more importance to meta-tags and number of sites linking to your site, and displays the results accordingly. On the other hand, Google calls it page rank by including few more parameters.

It hardly makes any difference. Both search engines give preference to good linking, good content and good traffic.