1. The vast majority of searchers assume that the anchor text shown on Google SERPs pages is the title of the page. So in the real world of the internet, there is effectively no difference.
2. Just because my web pages or your web pages sometimes use different or varied anchor text, that's not an excuse for Google to do it. Google has a responsibilty to the public, and that includes not using deceptive titles in its SERPs.
3. SO as I already said, it's unethical for Google to display anchor text that doesn't match the HTML page title.