Link and domain in different search engines represent different meaning.
Baidu, link does not represent a instruction, just a common key word. search results are contains such a keyword phrase ( all of the web page, and other common keywords search the same. And not find reverse link.
Google, the search is reverse link, but contains only website all reverse link a few. We recommend using Google webmaster tools check website all reverse link.
Yahoo, the search is reverse link, but need to be in before the domain name with "http://", such as: link: note: domain name with and without "WWW" the result is not the same.
Baidu, check your web page content contains some key words. Such as: search results is a key word group ( of all web pages. Similarly, domain: seo refers to include seo all web, and direct search seo similar. If you want to find how many web content contains your web site, domain can come in handy.
Google, domain doesn't mean a command. Just a common key word.
Yahoo, and as site. Search domain name, all the included web page.