According to the Searchengineland.com story, the smoking gun is that Bing does not offer a correction for "torsoraphy" yet returns the Wikipedia article. http://searchengineland.com/google-bing-is-cheating-copying-...

But the difference is really in what they do after they get the results from Wikipedia. Google searches for the term returned by the Wikimedia engine and offers it as the intended spelling. Per the screenshots, Bing returns the Wikipedia page, a page related to it's contents (long island surgery) and the results from Amazon (plus whatever else isn't shown).

Bing appears to offer broader searches when faced with ambiguity, whereas Google takes the results of the Wikimedia engine as gospel.